That completely changes the question because it gives you obvious deniability, whereas the lever probably does not. Especially if witnessed.

That matters legally (accidental death) versus intent (mens rea, murder).

It also matters socially, because you can deny that you made any choice even though you may have chosen (assuming you only do it once). You can even deny it to yourself.

It does beg the question: who set the trolley up to kill people, and why did you happen to be standing on the trigger?

It may have legal and social differences, but (imo) it should not have moral differences. Either way, there are two outcomes and you're picking one.

I'm just trying to poke at the gp's idea (paraphrasing) that inaction is morally blameless.

I think inaction refers to intent, not the way the wind blows. In the case of the hair trigger, I’d be morally obligated to stand very still, but it wouldn’t be particularly blameworthy if I happened to falter. This is in contrast to the normal switch, where I’d be to blame if I pulled it.