Maybe. BC. relies on Alberta for 90% of its petroleum products, only a fool would think they couldn't cause major trouble without going so far as cutting off all supply.
It doesn’t matter. Only a complete idiot would think that this wouldn’t be overturned quickly... with compensation having to be paid to BC and oil companies, and probably Canada too.
The Government of Canada owns the pipeline.
https://www.cbc.ca/amp/1.5101561Bakan says it's not just the B.C. government that would challenge a turn-off-the-taps law. Distributors from the private sector and suppliers in Alberta will most likely challenge it in court as well.
"It's an economic hit to them because they are losing a market," Bakan said.