I'm a bit surprised Cairns dropped him
According to the press release, Mennenga asked to be released to go back home to NZ. It would seem the Taipans were happy to agree with this. They already have Waardenburg and Gak on the books for next season and presumably will be looking for an import big as well, so I don't think this is a huge loss. I also think Mennenga was frustrated with the court time he got and that was probably not going to change next season.
As for him liking to shoot the 3, he was encouraged by the players and coaching staff to shoot the 3 more often. When that came off he was good however I agree with Dunkman that his inside play wasn't always the best.