Hoping this is not the typical pro-con external safety debate that is so common. Better sample of experienced people on this forum.
If you have a pistol with an external safety (1911, etc.), and assuming you train the hell out of it....and if the fight is 6 yards down to grappling distance or otherwise up close, personal and ugly QUICKLY and unexpectedly.
For this specific case, is an external safety:
1. A hindrance no matter how much you practice (due to the unexpected, etc.)
2. A wash compared to the other options (net impact zero as long as you are well practiced)
3. A benefit (preventing the assailant/perp/etc. from forcing an unwanted discharge, etc.)
Or none of the above and something else?
Again, this question assumes you have spent significant time training that weapon with that particular safety and the fight is sudden and bad breath distance or close enough to get that way in a second or two.