Limonadinis is 100 percent correct about the fact that it is not random.
If Turbosquid locks you out of their account even if they do not tell you a reason usually you fall into one of these categories;
1. Your models are not good enough to be on their site because you don't have good skills in 3d modeling or you are still learning.
2. They do not like what you are writing on their blog and are not happy if you complain in any way about their site or would like them to make some changes to promote a better community and allow more people to share in profit.
3. They noticed you have some amazing models they feel they can steal legally from you since you agreed to put them on their site and resell by making some small mods and can sell to 3rd parties.
4. You are undercutting the market by selling lower than they would like you to sell even though they false advertise you can sell at whatever price you want to without limit.
5. They did some research on you personally and they just plain do not want you to be part of their small so called special group, so they black list you and you can never even rejoin their site later.
6. You are doing really well and are taking away to much business from the top group of artists who make the most money on turbosquid.
They will never admit to any of this but these are the real reasons why people get kicked off Turbosquid and why people should never join Turbosquid.
Turbosquid is only for people who have been in the system and have somehow managed to thrive by skill or luck and are doing well there.