What is the right process though? I don't understand what the posing and rewrap is trying to do. Fix deformation?
So historically, to port a clothing that is originally fitted to a different pose other than T pose, there are usually 2 routes:
A: edit the cloth base mesh to fit the g2 T-Pose, then import.
B: pose g2 mesh to fit the clothes, then import that g2 pose as a morph. Then import the clothing, wrap to the morphed g2.
If you can do A easily without losing much of the clothing's original shape or details, there is no reason to go route B as it is more effort.
However depending on what clothing mesh you are dealing with, some times trying to fit it to T-Pose can be problematic. Skin tight clothes are usually fine, but heels, baggy pants, thick coats etc can prove to be difficult. This is why a lot of people wrap heels onto a heel posed custom morph to get the best result.
So with this plugin's posing function really is meant for when you already need to go B. It can save you the trouble of creating and using a custom morph just to pose the character, and of course the plugin provides finer control on wrap results.
If you already can fit the clothing to T-Pose with good result, there is really no reason to do posing in the plugin.
Let me know.