Point is, you have to be awarded the new category/BES, etc. to get out of your lock. The existence of it alone does not free you from your seat lock. You can, however bid into the new category, then lateral out.

Ex: New hire is awarded SFO 777 FO in training. MCO base opens & said new hire bids & is awarded MCO 737 FO. The following vacancy, the same new hire lateral bids to ORD 737 FO. The end result is a transition (SFO 777 FO > ORD 737 FO) which would not have been possible under his present seat lock; although it requires “passing through” the new BES.