Ahmadis hate all Muslims in America and around the world.  Its no secret.  Recently, they asked Professor Brown if Ahmadis were Muslim.  He gave the standard opinion per the consensus of Scholars, basically, telling Ahmadis that they are non-Muslim.  This has infuriated Ahmadis, they now hate Professor Brown and are trolling him.

Professor Brown’s recent statements on Ahmadiyya on his FB page, Nov–2017
“””So is social media just packed Ahmadis who think that if they convince ME they are Muslims somehow that’s going to mean something? I keep saying, “Guys, I’m not the problem. I don’t know of ANY Muslim scholar who says you’re Muslim. Even if I did say that, I’d get pilloried for breaking with consensus.” But they just keep badgering me about how etc etc etc. I say, “Please, I’m genuinely asking for this, please find me a fatwa from a scholar saying Qadiyanis are Muslims.” They never reply to that! They just badger me more!”””