Tenure modding will get you a permanent ban. Gamerscore will get you a reset of gamerscore, and maybe if they want to be dickheads, a permaban. Either way, just don't mod it and its fine.
I wouldn't do Tenure, but I've done and have been doing GS modding and haven't gotten any accounts reset / banned. All have been a while, and I still keep doing it nothing happens.
The tenure will only get setback if you delete it off of your console and redone load it or download it to another console. If you leave it in your console, when they see it, you lr account will be permabanned.