This one, I can understand Tua not sliding. He had just gotten past the 1st down marker, but if he slides, he might have started it early and thus might get ruled short of the line of the gain and it being 4th down, with his pick 6, he didn't wanted to ensure he got the first down.
But, he does need to consider his future. At some point, he will clear the concussion protocol, but even with a mini break, of 10 days, he really should not be starting vs SEA next week. As for his NFL future, I agree, he needs to consider his future. No amount of money is worth your health. As the #5 pick and 5th year option, he will have made around $47 mill, so he's set for life. Even if he has to return most of the SB he just got on his new contract.