I don't think it will stick but bad optics as an excuse? Please.
You award a contract for nearly a billion dollars where no others are considered to a company that has given large sums of money to various family members over the years and that's not questionable? Then throw in you saying that the civil service made the decision and then its revealed that you lied about that because it was a cabinet decision and you didn't excuse yourself from the discussion as you are supposed to. Plus one of WE's heads is on video saying the PM called you and offered the contract and then he backtracks on that when there's outrage by people.
Aga Khan, SNC, WE, how many passes and excuses does one get? Heck I didn't mention the incident in BC where he sexually harrassed a reporter, something that would have ended others careers, the broken promises (changing the electoral system, being more open and transparent).