Great, I'm glad we agree he should have flown the flags at half staff when 2 elected Minnesota lawmakers were murdered. But when he chose to not do that, but to lower the flags immediately after personally announcing the murder of a right wing political podcaster/influencer, it comes across as very divisive. "If my team gets hurt, we mourn, if your team gets hurt, fuck em." That is what makes it feel like "there is a war about to erupt", its that type of attitude.
In terms of your second question, I think people (and bots I guess) are free to do what they want. I don't like celebrating someone's death personally, but I also don't like many other things I see people do on social media or in real life, but I don't try to control them or change that behaviour.
If an elected representative on the other hand were to celebrate the death of Charlie Kirk (or the Minnesota lawmakers like a republican senator did), there likely should be consequences for that action because of the position and power they hold. I think politicians should be held to a higher standard in general vs. the regular public, but unfortunately I think we actually allow them a much much lower bar.
I also generally am not a fan of super broad terms like "the left". I've seen so many people use the following terms interchangeably (I can't blame them as the president himself, their leader, taught them to do this through repetition): the left, communists, democrats, fascists, radical left, etc...
I lean left of center most of the time (although I didn't vote for Kamala and I did vote for George W) so would consider myself a moderate democrat. I don't want to be associated with the 1-5% "radical left". Similar to how I assume you may lean right of center (maybe not?), but you may not want to be associated with the far right radical elements that exist in that party.
We've drifted towards using super divisive language (starting from the top with the prez) which is a very common divide/conquer tactic used throughout history by the rich/powerful to control the masses.
I'd imagine in real life, if we were to share a meal, we'd agree on 80%+ of issues and perhaps even enjoy each others company.