Would it remove MTO from legal hell? I'm curious what the precedent is here. The bigger issue seems to be legal hell for everyone else: the new signs seem to imply that sticking to the lane lines is mere guidance and that drivers may, if they choose, simply ignore them. If the idea is for drivers who ignore the lines to potentially still be found at fault (there's still a sign!), then what have truckers gained from white-on-green signs? Either the lane lines are enforced or they're not.
For MTO, as their multi-lane roundabouts necessitate trucks straddling the lanes, and their
signs and publications reflect that, then basically if they install regulatory signs then the messaging is contradictory. And if there's a crash and they get sued (which happens all the time), then that's a huge hole in their defense.
The advantage for drivers is that they are not obligated to follow the lane designations. If they were regulatory, then failure to follow them would be a Highway Traffic Act charge. But since they're not, even in the event of a collision they could not be charged for that.
So basically the signs are there to help people find the right lane, but it's not demanding that they do so.
Trucks and buses all over the US and Canada have warnings on the back that warn of lane-straddling/splitting and wide turns, and both types of vehicles frequently ignore existing regulatory signage and markings to safely complete manoeuvres. I'm not aware of any jurisdiction that has laws on the books permitting either vehicle to legally do these things, but its understood that they must. When a crash occurs, it is not the road authority who is found liable but those involved: if you search "truck wide right turn", 90% of the results are law firms looking to represent those involved in crashes. None of the pages seem to imply any DOT or MOT is responsible.
If an intersection's design will not accommodate the appropriate design vehicle (eg, a transport truck), then it probably would be irresponsible to put a lane designation on it. But that's up to them.
In terms of those law firms, yes, they are representing the victims of those crashes. And in addition to the trucking company, the driver and/or their insurance company, they will most assuredly sue the road authority as well. And the condition and messaging of the signs in the area will be one of the first things they look at.