Oh, I'm rather happy she never showed up and was at the time. But, I do believe there had been an agreement when they allowed DB to guest shot on BtVS for Chosen that SMG would return the favor.

Of course she was perfectly entitled to do whatever she wanted or needed for herself. I only began really rolling my eyes about it when she started talking about how much she'd wanted to do the finale but that she'd been shut out of returning because Fox refused her stipulations to show up. The show had offered four opportunities and she didn't have the time. By the time the finale filming had rolled around the show really deserved to focus on its own characters and not on Buffy.