No, this decision came from the Minister's office. There has been discussion of these and other topics at the committee level, but at the end of the day, the committee work is really just about providing education and guidance to ministry staffers and other parties.
I don't have any sources, but am willing to bet there is something. When I worked on the provincial electricity incentive programs, quite a bit of effort was expended to determine the effectiveness of the rebates and the resulting energy savings taking into account many variables. One of those variables was the idea of "free-ridership", in other words those who would have taken the conservation measures even without the rebates. The goal is to create a program that minimizes free-ridership. Not to have done this would have been reckless when spending dollars on conservation programs. In those programs, we were at least able to determine that the cost to save a kWh of consumption or kW of demand was lower than the cost of new build to generate it.
Now with the EV rebate program, I'm willing to bet that that there is an element of political partisanship mixed in for good measure as well. It is not in the nature of Left Wing governments to treat "the rich" the same as "the poor". They would be sensitive to even the idea of providing a "handout" to someone who can already afford a $75k+ car.
I wonder what the level of free-ridership actually was for Tesla purchasers? How many would have purchased the car either way? If that number is high (meaning would have bought the car even without the rebate), then the idea of a taxpayer funded incentive would indeed be a bad idea because clearly no incentive to change behavior is needed.
If this is to be a reward program, then anyone who purchases an EV should get the same level of reward money... but that was never the intent.
So circling back to @green1's original premise, funding may better be spent on infrastructure than on vehicle purchase incentives.