Historically, when someone was afraid of being "scooped" on an announcement they hadn't adequately polished, they would instead write a quick and dirty (and usually long-winded, because editing takes time) summary of their work—and then release an anagram of said summary. That way they could prove later that they had, in fact, gotten there first. Nowadays I expect we would use a hash function instead of an anagram, but the same idea applies. Put your idea in tangible form, even if the description sucks. Maybe you won't have to release it, but if someone else then tries to undercut you by throwing millions of dollars of tokens at the same problem, you can still show that you got there first.
It's unfortunate that it has come to this, but it's not a novel problem. Annoying and unsatisfactory solutions already exist.