If a transman wants to keep his name, he should be allowed to do that and it’s none of your business
If a transman wants to pick a name very similar to his dead name (Samantha to Sam, Jane to Jack, etc), he should be totally allowed. It’s a little cliche, but to some people it’s a reminder about where they came from.
If a transman wants to pick a name from a fictional media that they enjoy, DO NOT chastise them for it. That is one of the rudest things you could possibly do.
If a transman wants to pick a very unique name or a plain name with a unique spelling (like Nic instead of Nick), he should be allowed to without getting weird looks.
If a transman wants to pick a very regular run of the mill name to make himself feel comfortable, support him.
It may not be what YOU would choose but guess what. It’s not YOUR choice.