Not of SoftBank, but of WeWork (looked it up: chairman of the board, holding lots of shares). If SoftBank wants free reign to "fix" WeWork as they think is best, they need to buy him out or otherwise convince him that it's in his best interest to let them.
EDIT: not majority of shares/voting power, he gave that up when stepping down
He still has outweighted voting rights on his shares I think, but now at a non-majority level by the seems of it (I think the old model was 10 votes per share vs most other shareholders 1).
EDIT: not majority of shares/voting power, he gave that up when stepping down