if I could only stop an agression from your side by violating your property

That wouldn't be a violation. At least the Rothbardian take, as I understand it, is that the use of defensive force is permitted, and not a transgression or violation (subject to the principle of proportionality). Or another way of looking at it, the (would be) violator of another's rights forfeits a measure of his own property rights when doing so.

But the opposite is true as well. In the end, transgression is a form of aggression

I'm in favour of dropping that way of using the term aggression altogether, for the reasons mentioned in this article.

So, not sure this is adding anything meaninful (besides adding a twist to the NAP in order to make it even more appealing for anarcho-capitalists).

I'd say it makes it's a more accurate as well as more understandable term, with no disadvantages that I can think of that aren't also shared by the NAP term. That's already a big win imo.