There’s absolutely no way I’d consider a 2.20 connection at SEA on separate tickets, even with pre-clearance at YYC. WS will interline bags to BA but only on a through ticket so you will have to collect them, re-check and re-clear security, which on the best of days can only be described as a zoo. Even the Port of Seattle says to allow up to 3 hours. Personally, I’d take the AS option.