Sort of yes. I should mention though, having a US visa has no effect in this case. The moment you tell them the purpose of entry is to flag pole for PR, they are going to give you a paper refusal, since you do not actually intend to go to US.
But yes you walk to the US immigration, they will give you a paper refusal, you walk to Canada side, show them that and complete your landing. Officially it doesn't really count as a refusal.
But to be safe, if you are ever applying for a visa latter and asked the question "have you ever been refused entry / visa bla bla", its better to mention I flag polled for getting my PR.