In certain conditions, a safety stop can be aborted. Personaly, If the situation was a strong current in a safety stop, which made it uncomfortable, I'd abort the stop, and keep myself on the concervative side for the rest of the day. Safety stops are not mandatory, and all diving tables are built to work without it. It's just another precoution, that is up to you as a diver to asses and decide it's nessesity under the present conditions. This, ofcourse has nothing to do with mandatory deompression stops. those should never be aborted, unless a life-threatning situation ocures (a hungry shark, a storm), where you'd be safer seriously risking DCS.