I'm not quite sure what you're trying to communicate here. The fact that you did all bookings and cancellations on the phone with UA has no bearing on it. The notion of "They let me do it, and should have not allowed it at the time had it been in violation of the rules" doesn't work. The front-line UA reservation agent you deal with isn't doing a detailed data analysis on your history with UA. It would be the overall pattern of bookings and cancellation that would matter. They would look at the totality of the situation and make a determination, with a) you not being able to rebut their judgement based on micro-interpretations of rules, and b) more broadly, you not having a forum to present any sort of explanation, defense, or rebuttal. Once they decide that you've gone past the line, that's pretty much it. But, at least as far as the situations we've been privy to here on FT on the various US airlines that have taken such action, they don't seem to have a trigger finger, and only take such action on things like this when the situation is egregious and way over the top (that is, it always seem that way once we get the whole story, despite initial protests to the contrary by those affected). I think most people have a sixth sense as to whether they're over the line or not in these situations, although some seem to think that the line doesn't matter or should not matter (not that it helps in the end).

Even if challenged in court, as the plaintiff, it would be the passenger that had the burden of proof.