Then which act (or accusation thereof) is not antisemitic in that logic?

Looting or stealing land? Totally the cliche of the grabby jew.

Murder? Totally the well poison legend.

If everything is antisemitic, nothing is. And I'm really baffled how many people (you obviously included) don't see how that logic is extremely dangerous to the people they claim they want to protect.

This specific case is most likely a hoax, but calling the allegations antisemitic, just on the basis of whatever bad excuse for a reason you presented here, is just as dangerous as just believing the hoax.