I'm not sure why people would be surprised by this, Horgan never really positioned himself as a save the planet environmentalist. In my eyes it seemed like he stayed true to the labour roots of the NDP (for better or for worse) which generally means being pro-resource extraction be it logging, mining, or even fossil fuel extraction. As far as I can remember, the only anti-resource extraction policy the NDP really had under Horgan was opposition to TMX which ultimately was Albertan resource extraction, not BC's.
Also FWIW metallurgical coal is no better for the environment than thermal coal; Carbon is carbon regardless of the source. It's just that there doesn't seem to be anything close to a good alternative at the moment. I'm personally of the opinion that it's pretty important to reduce carbon emissions but for the time being it's probably more important that we can manufacture steel.
Reducing the amount of thermal coal used is a better fight to fight at the moment.
---
On the other other hand, are we sure this isn't an April Fool's joke? No one else is reporting this besides the G&M.