I suggest putting the blurb somewhere in your employment history. Your LinkedIn profile gets scraped and imported by various recruiting software. They often don't import the bio blurb (although they probably should).
This won't eliminate the spam, but will increase your chance of a recruiter seeing the blurb.
Are you trying to force them to see the blurb though? Van Halen could have put a callout to the brown M&M clause in a very prominent place in the contract, had a lot more venues see the clause and, by so doing, make it no longer a useful measurement of their attention to detail and level of effort.
This won't eliminate the spam, but will increase your chance of a recruiter seeing the blurb.