It doesn’t matter what price they bought SpaceX stock for. They could have gotten it for free. Any gain prior to Google’s investment could be realized prior to Google giving SpaceX even more money. What matters is the return on investment for the $12B/year into SpaceX.

In order get that back by “pumping” SpaceX stock, SpaceX market cap would have had to increase $200B based on that investment, and then Google would need to sell the stock.