It's because the modus operandi of war mongers, since before world war 1 has always been to agitate for wars that they don't want to fight for themselves. We are talking about nuclear war here, the bad faith argument is to imply that being against it is a sign of being a paid Russian shill. I guess the Pentagon is full of said shills, since they have never even hinted towards a direct war against Russia, or wanted to get directly (by means of troops on the ground) involved in one.
Now I agree that sometimes it's simply not realistic to go all "well do it yourself then". But in this case, Ukraine accepts, trains and equips volunteers. It's not a hypothetical.