This is one of those incidents where people just need to concede to common sense. (even if it means :gasp: letting the other side win in certain circumstances)
While marijuana is legal in most states now (which I feel is a good thing btw)
Employing underaged, undocumented people to work in in that field, is not.
This is one of those "pick your battles" situations (at least if you want objections to be taken seriously)
Gun stores are also legal in most states, if a gun store owner was employing underaged people (against the law) to process gun sale transactions, the "it's no big deal" people for this story, would think it was a much bigger deal.
My advice to more liberal people on this one is "don't take the bait".
Don't advocate for a position that's objectively stupid just so you can "oppose the Trump administration", this is exactly the kind of ammo they want to use against you.
Any legitimate gripes you may have with Trump's ICE policies are now going to be immediately met with "Yeah? You're the same people who defended 14 year olds working at pot farms so what value does your opinion have?"