I can fault them. As someone on the left, I dislike not having another choice besides Dems but for real there are far better ways to get the conversation more left than playing spoiler.
The thing about our shit system is you need to have heavy majorities in Congress on top of winning the electoral college if you want to be able to enact any change besides tearing things down. Spoiler candidates handicap that possibility.
There's way too many people who think that simple majorities mean it's enough to get stuff done but they at best (and as evidenced by the last 15 years) barely keep the status quo afloat.