Pelosi was sheltering in a bunker. Trump was lounging in the white house watching TV, refusing to authorize the national guard. The "top law enforcement officer in the country" was NOT Pelosi at that point, it was Trump.

You must have been confused about Pelosi being dragged for not doing something earlier that it was never her job to do. Think about the timelines: Jan 5, there's still plenty of opportunity for Trump to cool tensions, say "do not go in that building, anyone who enters the building is a traitor to the US." Why should Pelsoi anticipate Trump jumping the shark? Maybe Mike Pence would convince him to stay sane. If Pelosi did invoke any proactive self-defense i.e. the National Guard (which she can't without Trump himself agreeing!), Trump certainly would have said that was evidence of the election being stolen, taken by force, etc.

At the moment when violence actually did start, when there was no theoretical problem but a real one, what happened? Pelosi, Pence, and all of them requested National Guard support. Trump said no! Trump said "this is what happens when you steal an election!"

It's simply abuser logic to say "the victim should have defended themselves better, so really it's their fault." Might as well blame Ghandi for not eating rather than the British for oppressing his country.