If you are scared of standing up for what is right, and it doesn't require a weapon just a spine, then at least take 1 minute when you get to the car and make a call to TWRA.
I am sorry but it just isn't hard to wait with them on the line until the guy gets to his vehicle, pass on the tag number and hang up. Let them do their job with solid info.
All cell phones have cameras and most have video capabilities, it would be easy to get evidence which would be powerful if just a little empathy was shown towards the resource and others who enjoy it.
I can assure you that the guys I know in this thread including me have done the above over and over, because we legitimately care. I am not saying you don't care, but complaining here while doing nothing there won't stop or solve anything.
Preaching about conservation while turning a blind eye to blatant poaching is hypocritical and we all should strive to help TWRA and the river when these lay up opportunities occur.