White paper: Vendor Kernels, Bugs and Stability

You can say what you want, but the GPL deliberately does not define what "preferred form" means. And the "For an executable work, ..." part doesn't change that, because it it self refers to "source code" - it clarifies that the executable work includes the "source code" for X, Y and Z. And "source code" means "the preferred form for modifications".

You may indeed argue that the preferred form is a text file.

However, if you are a company that has deliberately stripped away context that you yourself use for hosting and modifying said source code as part of your commercial operation, and you have made that deliberate act in order to frustrate others who also wish to modify said source code, then I - if it mattered to me and I were a copyright holder - could well argue to a court that the form you have provided is clearly not the form you prefer to use yourself for making modifications, and that you have therefore violated the licence I gave you.

E.g., I - as your upstream - could well be trying to follow along with what you're doing to my code, so that I can cherry-pick the good bits to integrate back into the code. Your deliberate obfuscation, done to keep for yourself the preferred form of modifications and hence frustrate others from picking out what you changed, I would argue as being clearly against the wording of the licence.

The form you prefer to use internally, versus the form you chose to release, would be prima facie evidence of your failure to honour the licence.

Who would win, who knows. But I don't think your position would be 100% safe.