They have a law in Florida they could have used to seize his firearms temporarily until they could determine he was indeed a fruitcake.
Who cares if they already have a law. Make a new law that is the same as the old law. You are doing something. And if they point that out then you can make it a crime to not follow up on laws. Just don’t do nothing. Pass a law that sounds and is reasonable. It will inoculate Trump from signing any further laws.
More laws aren't the issue. The authorities in Broward who liberals depend on to protect us wouldn't have done a thing. As to you can make it a crime to not follow up on laws I don't disagree. I hope the feds prosecute the mayor of Oakland for obstruction. There are laws regarding malfeasance, though removal is usually the solution. No one, including the Governor, seems to want to act on that. Civil liability would seem the be the best chance, but with judgements against the negligent individuals, not the taxpayers. Maybe some of FR's lawyers could fill in legal remedies. I doubt we need new laws. One possibly, protecting taxpayers from judgments due to gross negligence on the part of officials. I'll also note, these are and should be state issues. Beyond NICS I don't see any reason for federal involvement.