If you only care about contributing improvements, no, it doesn’t matter.

If you want to at least be recognized as an author, and be able to say “I made this”, the license opposes that.

Waiver of Rights: You waive any rights to claim authorship of the contributions […]

I don’t know how they intend to accept contributions though. I guess code blocks in tickets or patch files? Forking is not allowed, so the typical fork + branch + create a pull request does not work.