To be fair I didn't really look into the details until now. The low in Canada is just a vigorous northern stream s/w. It's not like a storm developed over the plains and drove into the block. So I guess it's plausible.
To put it simply, the gfs op has a strong southern stream s/w and weaker northern stream which allows heights to rise and the storm comes up the coast. Note the higher heights on the EC than the para.
The para has a weaker, slower southern stream s/w and a stronger northern stream keeping heights on the EC much lower. Even if the southern stream were stronger this run it wouldn't come up the coast.
Btw, I'm legit laughing at breaking down a day 9/10 op run but it's always fun to learn I guess.