Wait that's it?

This is so trivial to break it's not worth anything. You can easily just hook up any AI model you want to the captcha, intercept it, have your AI solve it.

Or, you can just script it so if you do have an agent authenticated to Moltbook, you type whatever comment or post you want to your agent, then it solves the captcha and posts your text.

Basically, this method is as about as full of holes as a sieve.