If it is achievable, that would be a game changer for the kit wine universe wouldn’t it be?
There's nothing stopping you from inoculating a kit with MLB. It's wine, and if there is malic acid, it will get converted to lactic. However, if you do this, DO NOT add sorbate, as it reacts badly with MLB.
In addition, the reputable vendors balance the acid in their kits. Do MLF, and it changes that balance. Of course, as someone pointed out, the "balance" of the kit is the vendor's choice and you might want a different balance.
However, I think of this as similar to cold stabilization -- a lot of folks want to cold stabilize their wines. However, if the wine doesn't have excess tartaric acid, it doesn't do anything. Some wines benefit from specific techniques. Others do not. Ask yourself what positive benefit you will achieve by using any technique.
Here's a thought -- reserve a gallon of a kit and store it elsewhere. Inoculate the remaining 5 gallons with MLB and let it run it's course. At the year mark, compare both samples to experience the differences, if any.