I'm sorry, but computers can't magically know what is offensive... I mean look at the censoring on global...
It would take too much time and effort for SC to try and let you have custom shields without offensiveness. There have been many other suggestions that allow custom shields without offensiveness, so you might want to find one of those.
Cheers! (and this thread s really old....)
One way for folks to reduce offensiveness is to not get offended.
