Aren't you effectively trusting that service not to front run you?

Yes, the only other way is to mine it yourself. They are a public company that run their own miners if it makes you feel any better.

If you were designing this puzzle, could you do better so that this wasn't necessary? Maybe a two step protocol:

- Send some money to an address, which would temporarily stop accepting money from anywhere else. The fee gives the sender the exclusive right to solve the puzzle for, say, 15 blocks.

- After that transaction is validated, a second transaction (which now cannot be forged by bots) can be sent through.

I am pretty sure you could do something like this on Ethereum but I don't know if the BTC protocol would allow this. I also know very little about the guts of the respective VMs in general.

So there is an avenue to sue them / ruin their reputation

Please provide substantive feedback, I don't mind a downvote, but there is no learning opportunity without feedback content.

I wish HN eliminated downvotes without posting associated feedback

I stand by my point: pay peanuts, get monkeys.

If you don't take extra measures to ensure the safe reception of the reward, don't be surprised your security gauge turns out sticky.

How much would the solver have paid as a fee if he had used this service?