I believe the parent was mistakenly interpreting "lies told by your president" (emphasis mine) to be a #NotMyPresident kind of attack from a citizen across the aisle as opposed to an observation from a non-citizen. It sounds like the parent thought gp was a democratic who was insinuating that the current president and his political party are the only president and party who've told lies so egregious compared to those told by any other president from across the aisle that they're the only ones of consequence.

That's what I assume, but you know what they say about assumptions.