The flag carrier shouldn’t be able to use spartan abilities while carrying the flag. It makes too easy to capture it. In less than 10 seconds the flag is in the other base.
Interesting that just the other day there was a thread complaining that H5 makes it too difficult to capture the flag and so the matches run out of time at 0/0. I think flag is fine the way it is. The flag carrier can use most abilities, but so can everyone else with the addition of sprint.