EU can very well decide not to allow any product they please.

There are products that can't be sold on the EU because of health concerns. Threads is no different.

EU doesn't decide what product to allow or not. It has regulation, and any decisions are according to those rules, the same for all companies. Which is my point. They have no vendetta against Meta, as evidenced by Facebook and Instagram working fine in EU.

It can make particular businesses not profitable or even possible. Which is basically the issue for Threads at the moment.

Can you name one business that was banned by name, rather than by practice? (I think Huawei might qualify, but I'm not sure what else).

Huawei having problems security wise is generally a national issue and not an EU issue. Their products are being sold in the EU with no problems.