Is starlink that low power? The whole array of this one is 1.5kW. I thought starlink would be at least a few watts especially considering its bandwidth.

Yeah it's impressive and I know hams often spend a lot of money on gear. I don't though (I don't even do HF) but it's certainly cool to see.

But for incidental moon tracking I don't really see the need for a phased array other than the cool factor and the knowledge gained building it. Which are perfectly good reasons to do it of course! Just not technical ones.