I am speculating that WM with back injuries didn't need to go to the hangar often. Did business at his house so didn't know about the accumulation of stolen items. Finally, in Nov, took his date JC to look around:
Pretty soon, Wayne was calling her three or four times a day, Campbell said, and then that November, they met in person. He proudly showed her around the new hangar he had built at Waterloo Regional Airport for his business. Christie Blatchford: Victim had found love before his death, Millard’s trial hears
She pointed out it didn't look like an airplane hangar, but a car junk shop. WM ordered DM to clean it up and get rid of all that stuff, but that didn't fit with DM's ideas. WM went after the aircraft license himself and got it to get things moving infuriating DM.
Now, what I want to know is if indeed he was cleaning up the hangar, did he hang all the keys back up when he got back home just prior to finding his dad dead? Wonder if TB's key would have been hung there eventually? He didn't say they were backup keys as though there were other sets.