That seems like an overreaction, IMHO…
If the DM was constantly adversarial and pulling this trick in every single enouncter, ok, fine. That would be frustrating.
Doing it once, or doing a variety of different challenges, where this is one of them, and at other times other characters are affected, I think that’s totally fine. Actually, it’s not just fine, I would say it’s almost mandatory… a game that never stretches players’ creativity and never forces them to choose between two opposing effects… that would be boring. Not worthy of rage quitting, but certainly worthy of boredom quitting

…
It’s not true the character is out of options… they could still True Strike without Hex, or fire a non-TS crossbow shot with Hex. Let them do the math and figure out which option they prefer. That’s hardly unfair… just a slightly above average challenge.
The problem is the "participation ribbon philosophy" where every kid must win every contest they enter. No, that’s not how life works. You don’t always win every time. I sincerely hope you have a chance to win some of the time. But no one is entitled to win all of the time.