Given that the 4th platform at Weston is now complete, it is very plausible that they would start 30-min service to Bramalea (or possibly Mt Pleasant) in April.
If they were to implement alternating express and local service on UP Express, they would presumably time it with expanded local service on the Kitchener line to maintain a regular 15-minute headway at Weston and Bloor (alternating between Kitchener Local and Airport Local), so if the 30 min service to Bramalea is in fact starting, then the UP express/local change could plausibly accompany it.
However UPX DMUs are currently limited to 10 mph (16 km/h) past all UPX platforms. So express service would provide minimal benefit until that slow order is somehow resolved.
So my conclusion 'I don't know' but the claim is vaguely plausible.