I think that, as the author of an image (original or not), you can always ask for a comment to be removed, no matter what the reason or motivation is... even if you accepted both critical and non-critical comments... because it is your gallery after all. If that person took offense to your comment, that should be enough to get your comment removed. The same goes for any reply to this or any thread in the forum. If you don't like my reply here, you can get it removed (as a matter of speaking ;o))

We do not see things as they are. ǝɹɐ ǝʍ sɐ sƃuıɥʇ ǝǝs ǝʍ