I only think it's bad faith if an agreement was made in principal that was contingent on Ullmark leaving, or if he is asking for money and terms on a long-term deal that is completely out-of-line with the market, and he has no interest in entertaining alternatives like a short or mid-term contract. Knowing that Ullmark leaving grants him more leverage and taking advantage of that isn't bad faith.
I think 8x8 is more than fair in terms of AAV, but it is only part of the story. His comparables have all received NMCs for at least part of their contracts. Some have received signing bonuses. Without knowing the terms, I wouldn't assume he is acting in bad faith.
As I said in a previous post, this is a tricky negotiation because everybody seems to acknowledge that skill wise he is a comparable to the goalies in the approx. 8M camp, but due to the nature of how the Bruins built their team, he wasn't granted the same opportunity as someone like Sorokin.
I think that sometimes people are harder on players who take a hardline in negotiations, because there is a conflict of interest as a fan. We want to see our teams get players on the most favourable contracts as possible. Players don't always take a hardline because there is a lot to lose by not securing the bag. So it ends up as a big point of contention for fans when a player sits out and maximizes their leverage, which I understand, but it's the right of the player. They aren't doing anything wrong. They are negotiating with an employer.