>Since when is leasing capacity in a datacenter considered investing?

You misunderstand. The comment notes Google's initial shares, which is referring to a roughly 6.1% stake in SpaceX.

it's about squatting a percent that cannot be taken, there are many companies I know of who have large capacity reservations they don't use only because they hope to use it /soon/ and don't want to deal with cold start times. I remember when one used to be able to start a lambda labs on-demand h100 job and it'd start in 30 minutes, now you'd be lucky if it happened the same day

Why does one lease something? To provide value equal or better to the cost, no?

I dunno, I’ve never leased space in a datacenter without considering it an investment.

And one I expected to perform significantly better than either the risk free rate or just passive investment into the stock market.

Same reason I invest in capital equipment to put into the space I lease.