That's not heresy, that's standard vehicle dynamics.

When you move the cg forward, yes the vertical load on the front tires increases but the coefficient of friction for a tire actually DECREASES. For example:

Say a tire with a 1 pound vertical load has a friction coefficient of 1. Increase the load to 2 pounds, it might drop to .9. Lets see the effects of this:

A 4 pound car with the above tire on all four corners and equal static weight distribution would have a 1 pound vertical load on all four corners. 1 pound vertical load times 1.0 friction coefficient times 4 tires means the car has a maximum potential lateral acceleration (cornering force) of 4 pounds. So this car should corner at 1g (4 pound car). Of course, weight transfer and other factors means the car will never reach that maximum but let's ignore all that for now.

Now let's increase the car's weight to 8 pounds. Now each tire has a vertical load of 2 pounds, times a .9 coefficient of friction means each tire now can generate 1.8 pounds of cornering force times 4 tires equals 7.2 pounds total. So as you can see, the total grip has gone up but it has NOT gone up as much as the weight has since this car now weighs 8 pounds. 7.2 divided by 8 yields a maximum potential cornering ability of .9g. This is why lighter cars can corner harder than heavier cars, all else being equal.

So what about moving weight instead of increasing it? Well, if you move weight forward, yes you are increasing the vertical load on the front tires and therefore the grip of the front tires. But, you are also moving the cg forward, meaning the front tires will be "pushed outward" with more force. The amount of grip the front tires gain is not as much as the increase in outward lateral force. In addition, the rears are losing grip but not as much as the lateral force on them decreases. Therefore, the car gains understeer.

Now I can hear many people screaming, "but that's opposite from my experience." Well, there are circumstances that can cause opposite results, especially in offroad dirt racing. For instance, moving weight rearward can improve forward grip, reducing wheelspin and thus reducing understeer when on power.

Also, all those funny spikes, knobs, treads and whatnot in our tires combined with soft dirt can result in a tire's coefficient of friction increasing instead of decreasing with increased vertical load due to the spike being driven into the dirt more. This is actually pretty rare since most tracks are quite hard but in mud or sand, it can happen.

There is another situation that can cause reversal of the effect but I don't feel like mentioning it since it will only start an argument and it's only masking another problem rather than being an actual solution.