If you pause the game, the in-game timer should not be paused and should continue running. Ghost replays will not include the pauses, but the time will jump to account for the pauses. This still allows trials and trick ghosts to be completed using spacebar / pausing strategies, but the track leaderboards will reflect the players that completed the track the fastest in real time. Other racing games are built around real-time flow and I think spacebarring removes an aspect of skill that should normally be reflected on a best times leaderboard. If a ghost was paused during a run, maybe there could be two times tracked on the record - one for the total time and one for just the unpaused time.
