Only because in the current culture “Italian” isn’t generally considered to be a “race”.

But there’s nothing fundamentally distinguishing “of Italian descent” from the types of groups which are considered “races”.

If (hypothetically) someone were to hate people on the basis of those people being of Italian descent, this would be quite similar to if they were racist in a specific sense towards some group which is considered a “race”. However, presently, it would, I think, be significantly less harmful at the margin, because there are much fewer people that feel that way, and the overall harm scales super-linearly with the number-or-proportion-or-something of people who have the given prejudice.

That being said, I’m pretty sure that guy is trolling, and his complaint of anti-Italian racism is presumably insincere.