You provide a lot of solid information on here and the point isn't to combat you. I actually found out where the squeak was coming from myself. I'm not claiming to be a master tech by any means but its not my first time around a coilover. When discussing it with FOX, they said it sounds like a possible failed dust seal. The shop said the same thing after we lubed it.
Completely understand and it’s certainly not about wrong/right, only understanding the nature of the issue and what the contributing factors and resolution may be.
There are many times where a concern is identified and isolated to a part, but root cause of the part failure is unknown/undetermined. That results in repeat repairs, customer dissatisfaction, speculation, and high warranty cost. Which gets incorporated into the price of the next model year.
OE manufacturers only warranty what they engineer and build. Meaning if you take it apart, change something, put it back together and have an issue, the warranty does not cover that. Warranty is not comprehensive like insurance, it’s only a contract to repair a defect that is attributed to the design, engineering or assembly of vehicle as produced.
As an example, if one were to install an aftermarket air intake and a DTC sets (as we’ve seen many times…P04DB), it’s not the manufacturer’s responsibility to diagnose or repair, or “prove” that the modification caused the issue. But people will say “all they did” was change the intake assembly and “nobody else has problems”, which of course is baseless. If you change it from factory configuration, you’re now responsible for any resulting concerns/issues.