That's a fair question, and I think you have found a bug. The Power Station does not currently support PPS, which, I believe, is the charging protocol that allows for the Galaxy lines to charge at super-fast speeds. I suspect that the Samsung phone is trying to negotiate a PPS handshake, failing, and then defaulting back to USB2.0 charging (~2.5W). It's strange that it can be successful if something else is plugged into the other port first, we'll look into that. If you want, you could try turning ''off'' "super fast charging" on the Samsung phone just to see if that lets it directly charge via USB-PD. We'll get a fix in the works, and roll out PPS for the power station in the future.
You've done some good sleuthing on the power management, but I don't see anything that isn't "as designed". Essentially, the Power station will always prioritize an iFixit tool regardless of how much power it is currently drawing. We're working on a specification for better power balancing between the front ports based on how much power the devices are actually requesting, but there are a lot of edge cases that we want to make sure we get right before release to the public.
