They can say what they want, I'm sure there's some tuning/alignment that should/must be done for "mission critical" type P25 radios considering the intended role they play as opposed to business grade NXDN; however, I think they do this for 'CYA' reasons. Consider the local dealer/repair shop doing this work. You know that the software is probably going to get leaked, just like firmware, software and everything else and how much fun it would be for us to have access to programs that can change serial numbers and what not... not going to happen when you plug the leaks by keeping things all in-house.
Now, I suppose a lab-leak ala Moto could occur or skeygen, but I'm not holding my breath because at least in my case I'm perfectly happy with what I have, how it is.