You are quite right that BA has not adjusted for the fact that they are no longer funding the sponsored training, however the salary recouped under the previous system was not 100% of total training costs - arguably, they are now much closer to costs incurred for that first type rating, even though "your mate" would be required by BA to undergo training to BA procedures in the sim upon him joining the company.
Type freeze is largely irrelevant, as it does not prevent you from bidding for other fleets prior to that point, or indeed from being moved due to operational requirements - it is simply a restraint on you being anywhere other than at the bottom of the list of people from whom the fleet changes are decided.
Seniority is also much of a muchness, as with so long to command, and without a DB scheme, there is little merit in staying at one company if a better offer arises elsewhere...