Despite what you're implying, the devs have no duty to fix admin-reported problems using admin-dictated solutions.
They have already said they would accept a PR adding support for captchas. Someone will undoubtedly do this before long.
Until then, why the urgency? What is it that's preventing you from keeping your instance on 0.17?
A fork avoids this problem how?
Who's writing the code for the fork? If you see them, can you ask them to just submit the PR that the devs said they'll approve?