One of the best bits about that craft is that is has enough thrust and control to substantially change it's orbit multiple times during a mission. So it might want to intercept and take photos of various satellites or generally just point it's (presumably) ultra-elite camera at whatever it likes (north korea, iran, china) for calibration and testing purposes. It'll be going back up soon, I'd have thought. Probably several of them once Boeing have sorted out all the problems they turned up in this test flight.
It's not about taking out satellites, it's about recon. Imagine you are the US NRO (recon office) and have the ability to sidle up to enemy sats and take detailled photographs and scans of them for analysis by engineers down in the lab. that tells you all sorts about enemy capabilities and what they actually put into orbit rather than what they declare they are putting into orbit.They do not need expensive systems like this to take geo stationary satellites. That can easily be achieved by missiles launched from high altitude or the newer Multi Stage Anti Satellite Missiles known as ASM's.