"league did nothing to warn the Patriots" come on, get real. The league had no duty nor reason to warn the Patriots, in fact arguably they would be wrong to warn them. What you are suggesting seems akin to saying the mayor has a duty to warn you your neighbors have accused you of breaking the law, instead of keeping you ignorant while the police investigate. Just does not make any sense.
"dolts gone unpunished for illegally gauging a football on the sidelines" why would it be illegal? That ball was a Patriots ball that had been removed from play. It's not really any different from a fan catching a ball kicked through the uprights into the stands and gauging it, is it?
Face it, it was a sting, a trap. They all (league front office, probably plus execs from a team or two that are jealous and convinced the Patriots could not be so good for so long without cheating) thought the Pats were cheating, again, and that they could catch them and hang them for it. They were wrong, but too deep into it publicly by the time they discovered they were wrong, and they've had to keep doubling down ever since.