Re a comment earlier in the thread that the aircraft may have been deiced earlier.
According to LTD the viz was 1 mile in snow late in the afternoon. According to our viz charts if it was still daylight, then it would have been considered moderate snowfall, if it was dark, then this is considered heavy snowfall. According to the holdover charts for SAE type IV, there is NO published holdover times for heavy snow. In moderate it would be 35 mins. Not to say that he can't take off in heavy snow, or after 35 mins but an inspection of the fluid would be required, and if he isn't familiar with deicing and type IV fluid, and the signs of fluid breakdown, then it would be best if it was done by somebody else. I find it highly unlikely that an earlier spray at the gate in those conditions would have been sufficient.
I really don't understand the mindset that allows a "professional" crew to depart with snow on the wings. LTD did what needed to be done. In Canada, enforcement action is a possibility for departing with a contaminated wing, and for good reason. There is no excuse..