The software is brilliant (there's no dispute with the software and it's quality)
The lawsuit is a frivolous lawsuit (xenforo are expected to win this though nobody truly knows the outcome)
You purchasing at your own risks
The developers are not active or posted for a while on the forum so you may want to contact them through the contact form and you might get a reply about your question(s) that way.
I never said it was dying, it's going through a rough patch atm but then every forum software goes through this at sometime in their life.