I think there may have been some deliberate misdirection. I'm writing this after the US announced they have captured Maduro. If they had said they were going to do that he probably would have taken precautions. The subsequent justification may be that María Machado won the election, is the legitimate ruler and is entitled to ask for Maduro's removal with US assistance. Though who knows?
That justification feels weak because of how much it could parallel with Putin's special military operation, where Zelensky is an illegitimate president, Viktor Yanukovych is the legitimate ruler and is entitled to ask for Zelenksy's removal with Russian assistance.
I don't like how Trump has unilaterly decided this extreme of an action, but at the moment I am glad that this didn't fail like it did in Ukraine. I am still worried about what the aftermath will lead to. I don't think peace and democracy is having a particularly winning record at the moment.
He might have. Or he might well have come willingly, ordered his bodyguards not to shoot etc. figuring that he'll have a better chance being an alive headache for the US, than as an Allende being found dead by his own hand (supposedly), or as Saddam being found hiding in a pigsty somewhere 50 days later.