Sufis aren’t regarded as Muslims by the Muslim sects that trace back to Mohammed. It’s been said that Sufis predate Islam. In some ways they’re more akin to Buddhism than Islam.
All Muslim sects trace back to Mohammed.
In fact Sufis are actually Sunnis, differing from most by having what we would call a charismatic or mystical philosophy. They arent Shiites.
The real diff re Sufis is the extreme literalist school of Muslim interpretation, the Wahabbis, Deobandis, etc. that take more seriously the precise text of the Koran and the Hadiths, especially in judicial interpretation. Differ by some tiny degree and they will kill you.
The real cause for this though is politics. The Muslim Brotherhood wants power back in Egypt and they are doing what they think they need to to destabilize the government. Religion is a rationalization.