Of course it can get hurt even tuned well, and even without nitrous. But without the tune, it will get hurt for sure was the point.
The timing retard aspect is the main control to prevent excessive cylinder pressure, everything else being equal (no abnormal combustion going on). Don't really care about compression, but I do care about peak cylinder pressure. And we can measure that in the cyclinder, in real time, and have. I have WOT cylinder pressure traces from 30 psi boost, 30+ psi boost with 150 nitrous, etc. These traces are pretty rare.
Before taking on a nitrous project (or high boost project for that matter), it really helps to read through the article found on the web, "Nitrous: Naughty and Nice" by Keith Black's piston engineer John Erb. It doesn't tell the whole story, but it's one of the few "true" articles available out there among a sea of untruths. Personally I care about what is true and what is not. Not everyone does though. But this article is unlike the misleading, flashy headline we see everywhere- "Nitrous works by drastically increasing the cyclnder pressure". Misleading at best because yes, it CAN drastically increase the cylinder pressure if you allow it to, which will lead to broken engine parts, stat. And that method for increasing power seems to make intuitive sense at first thought, drastically increasing cylinder pressure is how the engine makes radically more power. But your job is to make sure it does NOT, because the engine structure just can't take it.
The real mechanism that allows radically increased power is not as obvious, but fortunately it allows us to do so without "drastically increasing cylinder pressure" and destroying the engine. If Erb's article isn't enough food for thought, I have WOT cylinder pressure traces that also prove it. The article will help explain why this is. At the very least it will help get the correct mind set. Give it a look.
TurboTR