Are Minelabs painted boards legal?

I have talked to a Friend of mine who is a para legal and posed this question about Minelab painting their circuit boards. I asked are minelab creating a repair monopoly by painting their circuit boards? Warranty cant be the issue because they wont even release schematics on by their own admission older \"obsolete\"models? What other reason would they have for withholding obsolete technology? Does anyone have a Friend that is a corporate lawyer to pose this question to? Thanks Nuggetbob