"Can" and "shouldn't" are two different things, the one having strictly to do with law, the other with political expediency. (And, of course, there's also the question of federal facilities and/or employees being directly threatened by violence, as in Portland). Strictly speaking, the president DOES have the power to send federal troops into a particular state or city to restore law and order.
What you're (apparently) advocating is that, as things stand, he SHOULDN'T do so at this time for political reasons, which I'd agree with. Wait till after the election, then let it fly. But if the "other side" has other plans in mind, and is intent on forcing his hand prior to the election (with slow Joe as their only hope, who can blame them?), then it becomes a tougher call.
If things reach the meltdown point prior to the election, then he could be considered derelict by NOT invoking the Insurrection Act. Long story short, it depends on what the other side does. Given how things are shaping up in Wisconsin right now, he could be given a pass by the majority of voters if they perceive he has no other choice than to send in troops. If this turns into a real, all-out shooting war, then all bets are off as to which course of action is more politically expedient. IMO, let the other side establish the ROE for the next two months, and react accordingly. But with Donald being Donald, who can say?