All the top high stakes players already have solvers that they've spent a lot of money developing and studying privately. They would definitely be upset with you, but by releasing the code you are democratizing the information to all the midstakes pros who want to study but don't have the resources to pay developers and solve the game privately.
b. How much more efficient is the improved search algorithm? the $150 number sounds like a couple of order of magnitudes..
b. It really depends on the game and the situation. It can be several orders of magnitude in six-player poker. In other games, it can be even more.
https://upswingpoker.com/isaac-haxton-pokerstars-partypoker/
I'm not sure the really provides strong opposition to the GP's claim.
By not releasing it, you're ensuring a higher concentration of money in the hands of a few, IMO.
Anyone with access to this source code could run a bot themselves, or employ someone to do so.
Plus, if you've accomplished this, no doubt someone can replicate it.