Should Christian denominations refuse to accept converts from Judaism?

[I spent the winter writing songs about getting better]

Of course not, and I don't think anyone who has argued that proselytization to Jews is any worse than any other type of proselytization has considered that this is the only logical conclusion, which creates all sorts of issues and that fundamentally it's an anti-Semitic policy ("We have a social grouping here, and membership is open to all people who are interested in joining...except for Jews.")

[I spent the winter writing songs about getting better]

If you are of the belief that people need saving, it's downright immoral not to "save" them though.

Although I do think the world's cultural heritage is weakened by the loss of interesting local and ancient religions in favour of Salafi Islam and boilerplate evangelical Christianity, the McDonalds of religions.

Evangelical Christianity is hardly uniform in any way, you're thinking of the megachurch type stuff obviously, but a lot is more equivalent to a recently opened but still independent and unique restaurant.

[I spent the winter writing songs about getting better]

Saying that "the logical conclusion" of proselytization towards Jews being discouraged is refusal of Jews into the group is ridiculous, and there's a very easy counterexample: Judaism does not proselytize -- at all -- but it still embraces sincere converts.

That's...actually a pretty good point.