That's a pettily literal and somewhat cynical snotty response IMO.
It’s pretty petty to piously trot out some well worn trope rather than making a case for any specific scenario.
It is a principle. Do nations stand by and watch other countries be brutally invaded? Alliances of nations?
Yes. Yes they do. They do all the time.
Do we stand aside and watch someone being bullied at work, or so we say something?
Again, people do, all the time. Mostly, people will only get involved if there is no retribution for themselves. Or if they have the power to intervene. Or it there is something in it for them.
Yes - I think everybody should do what they can and within their ability to help them all.
So why, as a nation, don’t we?
What does your cynical self suggest? That we turn our backs on everybody and expect everybody to turn their backs on us?
We’ve done that, to the list of nations and people I mentioned earlier. Why didn’t we help them?
I’m far from cynical, I’m a realist. There may well be good reasons for intervening. And the governments of the countries who are considering doing so should be honest about it. It isn’t ever about what is best for the nation under attack, it is political, and it is economic and it is also conveniently profitable for a whole lot of people with vested interests. I’d never expect them to admit to the latter, but they could be honest about the first two reasons and most would understand that.
May I never live in your world.