Let's just stipulate that's true: so what?
Obama drone-assassinated a US citizen who'd never been charged with a crime. Then, after assassinating him, Obama claimed the victim was an "imminent threat," but never bothered providing any evidence to that at all. Then a few weeks later Obama murdered that man's 16 year old son, also a US citizen and also not charged with any crime. Then Obama trotted Robert Gibbs out to say if the kid didn't want to die then he "should have had a more responsible father." And aside from people like Glenn Greenwald and Jeremy Scahill, who were eventually excommunicated from the Dem/lefty cool kids table over it, nobody said shit.
What Trump did re: Iran is vile and evil and illegal and reckless and counterproductive. But I swear: do not get into this partisan comparison game with Trumpkins. Not unless you are intimately familiar with just how much evil shit Barack Obama did, and most people aren't.
Admitting Obama was an evil sociopathic mass murderer means, for a lot of people, admitting that they were horribly wrong and that they need to stop idolizing and cherishing him and they're not willing to do that.
They still need him to be "cool" and charismatic and adorable and whatever other shit they spent a decade convincing themselves he was, because without that what do they have?