He didn't exit class A, he didn't hold it in the first place. Instead, he converted a small percentage of his class B into class A, and sold it.

Converting from Class B -> Class A opens a position in Class A.

Selling those Class A shares is still exiting a position in Class A.

But you're definitely right about the context!

He merely converted some Class B shares (non-publicly traded with 10X voting rights) to Class A (publicly traded) in order to sell them.