Actually, that might not be entirely accurate, as it was Tridge, Samba author, who reverse engineered the data format of BitKeeper for interoperability.

He never agreed to the BitKeeper license in the first place.

Calling him a member of Linus' team is a bit of a strech, because by that measure thousands are members of that team.

I certainly don't believe that everything in the world should be open source, but imo most formats are an exception.