The interesting thing about that argument is that it does not deny that Trump may have colluded with the Russians or obstructed justice. That is, even if you were right that the Dems are mad that they lost when they thought they would win, that would not diminish the significance of either collusion or obstruction. That is to say, Trump having won does not excuse either collusion or obstruction.
By all accounts, there are written questions now being answered. Original reporting was that the questions were just about collusion. Since then, however, reporting is that there are also written questions about obstruction, but that the Trump legal team is simply not going to answer those.
Now why would that be, and on what grounds? This may be the defense we heard earlier this year -- that Trump is legally entitled to obstruct in the form that he has, i.e. fire people and replace them with loyalists. Basically, that his right to hire who he wants supersedes the authority of the investigation. The problem with that argument, of course, is that ignores the why, i.e. why fire and replace with a loyalist?
What this is about is conspiracy tied to Roger Stone. Clearly, there is strong evidence that he and his associate were in contact with Wikileaks and knew in advance of the release of emails. The question is going to be, how much did Trump's team know about that, and specifically who knew? The fact is, Trump, Jr. is almost certainly facing an indictment at this point for perjury, having lied about all of that in the past, when it is clear that he was the conduit for information about it.
Who did he share that with? Manafort? Kush? Donnie, himself?