As said a couple posts ago, 1.20b won't delay the schedule of 1.21 release.

If anything delays 1.21 it will be 1.21 if that makes sense.

They have different teams working on different projects, in all liklihood the team working on Goobue has less to contribute to 1.21 than the other teams.

They don't just sit there and go, oh, 1.20b is done! We can work on 1.21 now! They probably have been working on parts of 1.21 since last July.