[rymiel]

He doesn't want to work on mold as part of Google or another large company like that because then Google would take ownership of the whole program; he wants to maintain ownership of it. It's mentioned in a tweet of his

[josephcsible]

Doesn't Google pay people to work on the Linux kernel, even though Google can't take ownership of the whole Linux kernel?

[tristan957]

Google owns employee code outside of work if I understand things correctly.

So Google only has copyright over the portions their employees have contributed.