Is the issue perception alone? Brand? What the industry advertises itself as? And the totality of their work doesn't matter?
A rather large difference between products that were made with slave labor and the military is that the overt, express purpose of the military is to kill people. Products made with slave labor are companies behaving badly, not companies fulfilling an express purpose.
> And the totality of their work doesn't matter?
If you find the purpose of the military objectionable, then no, that they also do some good isn't that important. Speaking generally, doing good deeds doesn't erase or forgive bad ones you have done.
It sounds to me like this is a case where you and your friend have fundamentally different moral codes with this sort of thing. It shouldn't affect your friendship. You could both just acknowledge that you have different opinions about this and let it go. Nobody agrees with anybody else about everything.