Google doesn't have to allow all transfers of extensions between different groups. The behavior of the new owner could have justified transferring it back.
As far as I can tell, Chris didn't immediately do anything that would have justified transferring it back either. Raymond was sick of dealing with low quality support requests, and so transferred the project to Chris. Over time, Raymond didn't like the direction Chris was taking the project, however, and started recommending his uBlock Origin fork for general consumption.