Dictators, like Maduro (and wannabe dictators), are notoriously coward. They won't risk their life against an enemy that will certainly bomb them from afar, but they would happily risk their whole country if that kept them safe.
Hell, even Trump wouldn't be that bold if he didn't know Venezuela has no will, or means, of putting him at risk.
According to his Wikipedia page, his downfall was the loss of the capital island of the Falkland islands. He was a true military dictator, abuses and all, but he might have understood that losing the Malvinas would be the end of his regime.
In that case, going against UK in an unwinnable war was a way to preserve his regime, as long as no bombings were made targeting him, so he could still protect his life. UK is not as ruthless in war as, say, USA or Israel, IMO that was a calculated risk to prolong the end.
Hell, even Trump wouldn't be that bold if he didn't know Venezuela has no will, or means, of putting him at risk.