> There is a purity spiral that organizations can enter when they start doing this

You are the one summoning that spiral by making a cheap gotcha wrt codeberg using Paypal.

The project apparently could and did move because the swith from github to codeberg wasn't that big of an impact, and because, while the new forge is not perfect, they feel the association is less severe. There is no "purity spiral" in that, just a pragmatic choice factoring in ethics.