"He is not regarded as a Muslim by anybody except other Ahmadis."

That's up there on the dumbness scale with those who say
'Catholics aren't Christians' or 'Mormans aren't Christians.'

Of course we have plenty of Muslims who claim one another
aren't. Lets see--the Sunnis say the Shiites aren't and
vice-versa.

And of course the Orthodox Jews claim that at least
some conservative and reformed Jews aren't...

Yes, Ahmadi is a bit of a fringe. That's well known.

But if it looks like a duck, quacks like a duck, and
above all CLAIMS TO BE A DUCK...