I, too, trust that we would never hit the button 1st - but that isn't what Trident is about in any case, and it makes his comments reasonably irrelevant.
Trident is our end-game, a 2nd strike system that, reasonably uniquely, cannot be stopped with a hit to our command and control chain.
It makes his comment that he 'wouldn't hit the button' in relation to Trident a little bit daft, because in the scenario that Trident is designed to tackle, London is already likely to be a radioactive ruin, he is likely to be dead and the Submarine Captain's will be acting from the Letter's of Last Resort which they are already carrying. It won't be his button to push.
It is not to be underestimated what effect that has - effectively, we can be turned to a radioactive slag, but whoever does it, WILL get hit back. That's a far bigger threat, £ for £ than any number of conventional Nukes.
Trident aside, though, I actually admire him for being willing to stand by his personal convictions, albeit I would be very wary of wanting him now as our Leader.
Then again, I was wary of him on an International stage anyway. I just can't see how he sits at a table with some of the people he would need to and gets taken seriously.