Both GP's and your example in effect mean "I'm fine with other people doing this, but I don't want to have anything to do with it, or at least be able to decide case-by-case."

Which is a valid stance IMO.

In the OP, a vibecoded UI when the whole project emphasizes "I did this myself, from scratch" is a bit awkward.

Does "I did this myself" mean they read all the relevant specs and then wrote the code - or did they just write the prompts themselves?

Edit: OP already answered and confirmed that they in fact did write the code themselves.