How? Unless I'm misunderstanding the word, "tampering" implies "making alterations to", and no aircraft systems are altered in any way - they are exactly as they were, doing exactly as they're programmed. (Ab)using the difference between implied programming and de-facto programming could be unauthorized access, but I don't see how that could possibly constitute tampering.
Not that I disagree with your overall point, just the tampering bit strikes me as particularly odd.
I think it's well-known that entertainment systems have to be isolated from main systems of the aircraft. I'm not an expert, but I know that it was the case that IFEs weren't safe, plane(s) went down because of that, so we no longer do that.
All this said, I totally agree with you that there is a non-negligible chance that abusing the network policies could lead to some charges, possibly even criminal charges. Or, at the very least, lead to some unpleasantness that surely isn't worth 30 bucks. Just not the charges you're mentioning.
Every thread on this topic has some hackers making bad assumptions about how law works based on naive definitions. You've got to understand that law doesn't operate on binary distinctions and that interpretation is an extremely moveable feast.
To give you some context:
Before writing that comment, I looked up a dictionary entry for "tampering", to be sure my knowledge of the ordinary meaning of the word is correct.
Then I looked up and did a quick cursory check on a bunch of laws that included the word, focusing on (but not limiting to) those that mentioned tampering with an aircraft or machinery, or tampering with communications technology of some sort.
During that check I found that everything I found either explicitly mentioned or implied making changes of some sort: alteration, removal, damage, concealment, obstruction, etc.. So while I haven't found an explicit legal definition I hoped for, I think it's fairly reasonable to assume that legal concept of tampering would generally conform to the dictionary definition in this regard.
And thus down the thread I made a suggestion that it's unlikely (no binary here) to apply to the situation. So I asked "how?", to see if I'm missing something, explaining that I personally don't see how "tampering" is applicable.
Yet, your comment suggests me that I wrote something wrong. While I recognize the "vehicle" example (that I happen to know about) is not entirely dissimilar to the "tampering" here, I'm still missing your point.
In practice - yes, that could happen I guess. I lived in Russia, I've seen a lot worse "creativity" from the courts.
Ideally, though, such "creative legalese" shouldn't be a thing, as it ultimately does more harm than good.