So because he wears a certain garb and a beard, he doesn't need to be fully investigated?
He is a jihadi/terrorist/maulvi/hafiz-e-Quran/charity organizer depending on who you ask.
The reality is that what he does is preach jihad while also doing charity work, but he is considered "loyal" to the state and does not support anti-Pakistan work.
But everyone knows that Jamaat-Dawa is same as Lashkar-e-Tayba. Sometimes some of his "followers" end up supporting "Al Qaeda" but they seem to disappear...
The other reality is that he is grown so public and open with his activities that UN has banned him and declared him as a terrorist.
We will not take action on him because his close ties to powerful people in the establishmen and he will expose all if we mess with him.
US will accept that as long as his people don't end up connected to another 9/11.
What will happen if that happens is open to question.
The guys like Ilyas Kashmiri, "Dr. Usman", "Maulana Fazlullah" etc. were all in similar position of Hafiz Sayeed not too long ago
Playing with fire and then disowning it is all the part of the game...