For your math to make sense, Google would have to sell its stake this year

There may be more to it than buying compute but what you're saying does not make sense for Google. More likely Google wants a good relationship with SpaceX and possibly to buoy the stock, but it's a bad NPV trade

On the other hand, google does not lose all the money in that deal. Computation is still expensive.

So at most they lose like 200M each month. Peanut compares to the potentially gain of the IPO.