Hasan al-Banna founded his organization "al-Ikhwan al-Muslimeen" upon the principle that anyone who says "Laa ilaaha illallaaha" can join his organization in order to work towards a collective goal - and this includes the Rafidah Shi'ah - for he strove to bring nearness, cordiality and unity between Ahl us-Sunnah and the Shi'ah, i.e. between Muslims and non-Muslims.

In any case, you will come to realise why they focus on this one particular Scholar, Shaykh Rabi bin Hadi al-Madkhali - it is because of the fact that Shaykh Rabi gave nasiha to Allaah, to His Book, to His Messenger and to the generality of the Muslims in exposing the falsehood and opposition to Islaam of the likes of Hasan al-Banna and Sayyid Qutb. Also because he was supported by the Scholars in that, some of whom even preceded him in some areas of refutation against these Innovators. They lament over the fact that this Shaykh spoke and refuted some of their figureheads, and in fact Imaam Ibn Uthaymeen has explicitly stated that this, the people only started tarnishing Shaykh Rabi with faults after he spoke about their rumooz (figureheads) - see this article. It is precisely for this reason that many of these rodents went out looking for "controversies" and "scandals" to try and tarnish the Shaykh, far-removed from any knowledge-based discussion of the actual issues.

So they went searching and found nothing of value to defend the likes of Sayyid Qutb and Hasan al-Banna except what was of a sensational, and "scandal-type" value to them: "Shaykh Rabi said Ibn Baz stabbed Salafiyyah in the back", and "The Mufti warns from Madkhalis" and "Ghudayan does not know Rabi" and "Rabi made Takfir of Qutb, and Banna and Jibrin", and so on and so on. Having been refuted on all knowledge-based issues pertaining to the innovated methodologies of al-Ikhwan al-Muslimeen, and the innovations, deviations and misguidance of its figureheads, these people could only hunt for what they saw as sensational, controversial, "scandals" through which to deceive others about the true and real underlying issues. However, people are not as gullible as these fools think, and they can easily discern the fact that these people are bankrupt, and actually have no money in their pockets. That's why all you are going to see is cheap shots, aspersions on personalities, but no discussions about the evidences against the methodologies that Qutb and Banna innovated and for which all the Scholars refuted them. And this is their actual grievance, it is resentment and hatred that drives these people, little else.

Hasan al-Banna: Ahl us-Sunnah and the Shiah are the Same, Upon Purity, United by the Kalimah

Shaykh Rabi bin Hadi al-Madkhali, (hafidhahullaah) stated, in the course of his refutation of Abu al-Hasan al-Misri's apologetic defence for al-Ikhwan al-Muslimeen (calling them Ahl ul-Ittibaa'!), documents Hasan al-Banna's efforts in uniting between the Sunnah and the Shiah. The Shaykh wrote, as occurs in (أبو الحسن يدافع بالباطل والعدوان عن الإخوان ودعاة حرية ووحدة الأديان ) "Abu al-Hasan Defends, in Falsehood and Transgression, the Ikhwaan, and the Callers to Freedom (of Belief) and Unity of Religions)", on p.22:

Al-Banna's Endeavour In Seriously Working For Nearness Between the Madhaahib and At the Head of them, the Raafidah

And in his latest book, "Dhikriyyaat, Laa Mudhakkaraat" (1st print, Dar al-I'tisaam, 1985), the Ustaadh, Umar at-Tilmisaanee says (pp. 249-250):

And in the forties from what I recall, Sayyid al-Qummee - and he is Shi'ite in his madhhab - came as a guest of the Ikhwaan at the main headquarters, and at this time, the Imaam, Shaheed (i.e. al-Banna) was [undertaking] serious action in bringing proximity between the madhaahib, so that the enemies of Islaam do not take the splitting between the madhaahib as a means through which they can work to tear apart the Islamic unity. We asked him one day about the extent of the difference between Ahl us-Sunnah and the Shiah, but he prohibited us from entering into the likes of these thorny issues which are not befitting for the Muslims to become occupied with, with the Muslims already upon what we see of separation, the enemies of Islaam work to kindle its fire, so we said to his eminence: We do not ask this due to partisanship or to widen the difference between the Muslims, but we ask due to knowledge because what is between the Sunnah and the Shiah (of difference) is mentioned in the authored books that are innumerable, and we do not have the time that will allow us to investigate all those sources. So he, may Allaah be pleased with him, said:

Know that Ahl us-Sunnah and the Shiah are Muslims, the kalima "There is none worthy of worship except Allaah and Muhammad is the Messenger of Allaah" unites them. And this is the foundation of the aqidah. And the Sunnah and the Shiah are the same (regarding that), and (they) are upon purity. As for the difference between them both, then it is in matters in which it is possible to bring them together.