Yes Sub zero has been doing this for a while. Also if you call tech support they request the customers info to later send them a letter stating that they can void their warranty if someone other then a factory authorize work on the unit. This is not true and it is not on the warranty. Subzero warranty is 2 years anything goes, 3-5 years seal system including parts an labor, and from 6-12 years seal system parts only. And yes what they are doing somewhat illegal but they know how to play their cards. One day someone will take them to curt for misleading the customers. Some where there they have to be braking some kind of industry or business law. I had training at the factory and use to work for one of their authorize servicers and man those machine are good looking but they brake more than a regular refrigerator. And to protect their equipment mistakes could be the reason for this.
Just continue to a good job. Ignore Subzero, keep a positive attitude, try to avoid calling subzero for tech help, that is an inmediate leter to your customer to scare them away from you.