Do you have any source to this? If this were the motive, why would more VCs not require their corporates to be formed as non-profits?

Because the donors didn't know the company was going to pivot to private. If VCs did that deliberately it would be completely illegal.

sounds like a very wink wink way to go about it

But the people who donated that money to the non-profit can't receive any profits? And the expected tax benefits of donating a dollar are always less than a dollar, so that doesn't make any sense.