It's actually surprisingly structured, with pretty clear rules. Among them are "bright lines" and "fuzzy lines". A bright line is something which forces an automatic response nobody likes, and it's backed by a lot of commitment. Not responding to an adversary crossing a bright line trashes your whole reputation and strongly signals you're weak.
The problem with bright lines is that once you state them, the other guy is free to do anything up to your line. It's like posting your final price in a classified post - nobody will ever offer you more. A fuzzy line is the solution: you say something like "if you move forward, I will do things you don't like", without saying how much forward or what things. Which forces the other guy to tip-toe around. You see A LOT of this between NATO and Russia in Ukraine.
Back to your point - nuclear attacks are a very clear bright line. One might say the final bright line, written in neon. They should be treated as such, and not watered down - if you say "bombing a power station is identical to nuclear attacks", you may make bombing power stations very slightly less likely, but you also normalize nuclear attacks by the same amount - and this is VERY BAD.