What I'm hoping is that the quasi-express like nature of UPX at the moment is just to appease the locals until a full-fledged GO REX system is operating on the corridor. When that's the case, the need for those UPX trains stopping there will virtually disappear. It's just that with no midday/night/weekend service on the Kitchener line, it's a tough pill to swallow to see trains passing by every 15 minutes and not stopping. But when you'll have GO REX trains running the same frequency or less, suddenly UPX trains stopping becomes much less important.
Even with non-electrified off-peak service on the Kitchener line, that should do the trick, although I think they'd need at least Lakeshore 30 min levels in order to really fill that gap.