TNT already said that they were going to massively downsize their own airline and increase the use of ground transport regardless of UPS buying them. So most of those TNT Airways guys would be out of a job no matter what.
UPS' MO is to not buy airlines or take on massive amounts of new employees. They want the customer base and the volume that those customers bring.
Since UPS is the purchaser, it's normal to want our own airline to do any additional flying that will result.