I think one important point is that the MOD haven't chosen the Puma, they've been forced to find a replacement with Draken choosing to end all of it's rotary wing business, I think they're making a reasonable best of a less than ideal scenario.
A question I haven't seen answered yet is hangarage in Brunei. The shed out there is only really suitable for 212's, I'd be surprised if a/three Puma(s) would fit. A year isn't very long to negotiate with local government and build a new facility, especially as I doubt they'd want to waste funds and resources on a new facility for the current operation with a different aircraft, only to change to a new aircraft and probably a new operation structure within approx 10 years.