Further, until they actually do solve upper stage reuse, it is an "if" which can kill the economics of the vehicle itself, let alone reach the eventual potential cost reductions necessary for space based data centres to be worthwhile.
If they do manage to reuse the upper stage, then they should have no problem exceeding falcon launch cadence. Starship is much easier to build than Falcon. Welding is simpler and less expensive than the carbon composites used on Falcon upper stages.
According to Google, the price threshold to make space make more sensible than building on the ground is $200/kg: https://arxiv.org/pdf/2511.19468
Without full reusability, the estimated cost for Starship to LEO is kinda hard to find (necessarily, given the design isn't yet finalised), Wikipedia says $100m/launch in expendable mode, and the SpaceX website* says 250 metric tonnes in expendable mode, which is $100e6/250 metric tonnes = $400/kg.
* at least it does at time of writing: https://www.spacex.com/vehicles/starship