Last time I checked, even the non live time/multiplayer options kept the clock ticking. Has this been changed?
Edit: Just checked. Multiplayer off, traffic off, live weather & time off. ESC to the options menu and the clock still runs, hence there is no actual pause as we traditionally know it, in MSFS. A lot of people are unaware of this fact.
Relating this to a replay function, if time cannot be stopped, it makes a replay feature substantially more complicated.