Who are you referring to? Both were banned. Ye was allowed back recently and was banned again days later for anti-semitic tweets:

https://www.google.com/search?q=kanye+banned+from+twitter https://www.google.com/search?q=trump+banned+from+twitter

*edit

Ye/Kanye's twitter was locked, not banned.

Kanye was banned? I thought they removed your content if you were banned.

Yep just clarified, restricted/locked, not banned.