Assuming bad faith without evidence is a big part of the issue here.
You specifically asked "What's the ulterior motive here?" which implies you think there is an ulterior motive. An ulterior motive would be acting in bad faith, since it would by definition be different than the expressed motive, since the reasoning was clearly expressed above.
Presentation matters. Whether you meant it to be or not, your statement is somewhat inflammatory, for the reasons I just outlined. In my opinion, it's also a very good reason why the temporary ban is a good idea.
I was very specific to outline an additional condition which I think makes all the difference, which is that you were presented with the reason for the action. Assuming an ulterior motive when you've already been given an explicit motive is assuming they are acting in bad faith, and that that they've provided a reason that does not match reality.
> I was skeptical about the reason dang
As to this, I'm not sure I have the same skepticism you do in this regard. HN has a history of flagging overly political stories, as it can often be hard to keep discussion civil. There seems to be less flagging of these as the election gets close, as it's more relevant to everyone involved, but trying to cut back after the election is past seems appropriate to me.