If I owned one of these, I wouldn't care whose fault it was.
I bought it from a certain company, it's their problem to fix - however they go about that.
Same with anything, I take it up with the only entity I have any "contract" with, and that's the company that made it and sells it to me.
Everything else is moot. It's for them to deal with.
And I'd already be putting a black-mark against their name that it was even possible for this to happen, let alone not know it was going to happen, let alone allow it to happen before they could counter it, let alone somehow require *me* to do something to fix it.
It's none of my business if the code was licenced, the bill was unpaid, the feud is unreasonable, whatever... If I bought a product, it needs to work. If it doesn't, I'd want my money back. And the only people I would concern myself with would be the people I bought the product from.
They can do all the mud-slinging, accusations, feuds, lawsuits etc. that they like. I don't want to be involved, and it's pretty unprofessional to have got this far to be airing your dirty laundry anyway.
And if they are saying it's the contractor being unprofessional? Well, who decided to go with that contractor and not replace them before shipping your product to the world and waiting for years for the problem to occur?