Okay, so you're trust is completely in one person having perfect design decisions and that he chooses to continue to maintain these tools in perpetuity.
You also state that tool may or may not be able interact with past files. Which means it might be useless.
Git is in the process of deprecating sha1, and you end up having the put flexibility in after a tool expands. It will likely keep supporting sha1 even after it is much more trivial to create collisions.
No one is getting locked out of their files created by an old version. There will be a migration path. The old code will be in git. Worst case, the spec is open, I can implement the spec myself in python, using pycryptodome and pyca/cryptography, it wouldn't be hard.
I trust his judgement much more than I trust the group that maintains gpg. Of course, actually, there is a community, Filippo is not working in a vacuum. Worst case, if Filippo stops maintaining it or makes bad decisions, someone else (or a group of people) will maintain it.
You also state that tool may or may not be able interact with past files. Which means it might be useless.
Git is in the process of deprecating sha1, and you end up having the put flexibility in after a tool expands. It will likely keep supporting sha1 even after it is much more trivial to create collisions.