Ginger, I see no harm whatsoever in voicing objection to the recent policy change. IMHO it is unlikely that this gov't will reverse it, but raising an objection to it now might make them think twice in the future before making such changes without appropriate consultation or notice. Or not.
One angle you may want to explore is whether this policy change stands to impact First Nations. A big part of the fuss/delays/uncertainty over the TransMountain expansion was driven by inadequate consultation with FN's.
The good ol' Official Opposition may be another place to go to raise a stink over the policy change (particularly if through FN's or other stakeholders inadequate consultation can be clearly illustrated). I don't recall hearing much (if anything) from Rachel and crew on the policy change, at least thus far. Rachel is now on about the parks eliminations, so maybe there's some common ground there with them.
While taking a run at the policy change is fine, efforts should in parallel be made to organize effective opposition/intervention into the regulatory approval process of this particular mine, should the company proceed with making such an application.