He also deleted tweets about Beyonce and Black Panther according to the articled linked below.

http://www.espn.com/nfl/draft2019/story/_/id/26470980/nick-bosa-nfl-draft-best-prospect-itching-return-field

Dude said he did it because he might be going to San Francisco.

That seemed like a real passive aggressive way to speak on stereotype that San Fran has long held.

Excerpt from the piece:

"I asked Nick the same question reporters always ask Cheryl: How are the brothers different? Joey is more competitive, Nick reluctantly admits, and has interests outside of football. (He'll make his acting debut with a small role in the final season of Game of Thrones on HBO this spring.) Nick loves football more, he says-"I was full-on into it from the time I was 7. Joey, not as much." He's also more politically minded. Last year he seemed to delight in posting political takes, including his support for President Trump, on Twitter and needling dissenters. (He also caused a minor social media stir by criticizing Beyonce, Black Panther and Colin Kaepernick, all eventually deleted.) As the combine drew near, though, his online behavior grew increasingly bland. I asked why he seemed to abandon something he had previously embraced."

"I had to," he says. "There is a chance I might end up in San Francisco."