Plugin is not supporting Matrix Aggregation, when activated through the Flexible Publish, i got the following message:

[Never seen - one hopes :-)] WARNING: Condition for Matrix Aggregation is configured for Set GitHub commit status (universal) which does not support aggregation

It can be helpfull when working with Matrix jobs, let's say you have 20 config per build then you could only post back to GitHub the overall build result from the parent job.