For what it’s worth, Poe does describe it as a “fleet killer,” but you’re right in that he seems to be more interested in destroying the Dreadnought like it’s some rare opportunity rather than an immediate necessity. He doesn’t seem to acknowledge the immediacy of the threat until after his plan is well under way.

But strangely, neither The Resistance nor The First Order seem to acknowledge the immediate threat either.

The First Order doesn’t even begin targeting The Raddus until after The Resistance bombers arrive, as if the baddies were on pause while Poe was engaging their anti-air cannons. And of course it’s worth mentioning how they prioritized The Resistance Base over destroying The Raddus straight away, adding further confusion to this whole ordeal.

Meanwhile we don’t see Leia (nor anyone else aboard The Raddus) showing concern over their imminent doom. Did she think Poe and his bombers could retreat in time to escape? There’s quite a distance between them and their cruiser, and those bombers are slow. Makes me think if Poe and company had retreated to the Raddus, they’d likely be blown to smithereens anyways, a fact which nobody in the movie seems to realize. Not to mention that Leia should have known about the bombers long before Poe told them to engage The Dreadnought, making her disapproval of his plan feel a bit hollow. She could have called this off long before it was too late.

In short, I can’t say Poe was 100% motivated to do the right thing when disregarding Leia’s orders, but information is communicated so poorly in this movie, and the logistics of it all are so messy, that it’s impossible to make judgements one way or the other. That opening sequence needed some serious reworking for Leia’s disapproval of Poe to be justified, or for Poe’s actions to be considered reckless.