I do not know what will happen, but I would not do it out of my gun. Seems like there could be a lot of down side verses the up side.
No down side unless he is using a Super Full (turkey) choke. I don't like to use a full choke on slugs but not much danger there either with most guns. The choke actually helps accuracy by centering the slug in the center of the bore making shots more consistent than with a cylinder bore. It and skeet choke are barely any choke at all. Most shooters that think much about it like to use 'M', I use IM with good results.
Good intentions will always be pleaded for any assumption of power. The Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern will, but they mean to govern. They promise to be good masters, but they mean to be masters.