Is it bull, or is it a naive expression of hope that the flight will get out... eventually.

MX or WX delays, they do happen.

The GA gains nothing by intentionally lieing to PX. With WX delays, you get "folks, we'll make a decision in 30 minutes. Stay near the gate/on the plane/whatever and we'll try to get this plane out soon." Then at that 30 minute decision point, you learn "well folks, ATC still hasn't cleared that route."

In a very dynamic and fluid situation with information and inputs from multiple disconnected sources the result is often chaos. But I don't think as a rule GAs intentionally lie.

They would much rather send you home early if the flight will be cancelled, or get you on the plane away from their gate if they possibly could.