I’d think it this way: Get the training anyway, hold off buying if that’s morally (and understandably so) difficult.
If shit hits the fan before you get one and/or it’s otherwise too late, there’ll be chances of obtaining one in the middle of the shitstorm one way or another. Maybe someone friendly has one, but never got around to proper training? Good thing you did. You can help out and try your best to utilise it as morally but also as professionally and efficiently as you can.
Slightly more long term, you can assist training others, if using one on live targets still feels objectionable (and rightly so!) to you.
Learning the craft and proper handling will not go to waste, if it starts looking even worse than it does now.
It can be good, too, to help others use the things more safely and otherwise properly. May save lives. And you need not take any, not in defense or otherwise, if that’s important to you.
And switch it towards absurdism and especially Camus towards the end. Having the “…but it is, or can be, actually good” angle really helps adapting that mindset to real life action and motivation.