Not all "fun driving" is reckless driving. Endangering other people is never right of course. But the majority of people with car hobbies are very safe drivers.
If driving is not really your interest, that's totally fine. I don't personally see much appeal to it either. But that doesn't mean you should yuck other people's yum.
I am not super knowledgeable about this side of thing - but it seems like the teams' argument is that the Flyers signed DeAngelo a year ago and not the Canes, so this clause technically shouldn't apply. Letter of the law vs the spirit of it.
We'll see what the league says. I would imagine that if the trade is put on hold, plans would change after the free agent market opens, and this doesn't end up happening.