The reason this prohibition exists is simple.
As we saw with the rescinded Bancroft Prize for history a few years ago, so called research about guns is often politically motivated fabrication and falsehood only de-bunked with great effort.
His credulity strains belief. As someone who is not familiar with his past work this line tells me he is either a fool or thinks I am one. While that may be the properly stated ethical position, anyone who has followed politically charged research subjects, knows this ethical principal if willfully and repeatedly ignored.
Kellerman is one of the biggest liars among the anti-gun “researchers”. Non-crime firearms injuries (and even total violence have been decreasing for years WITHOUT the interference of the “medical professionals”, who have no business talking about “gun business”, of which they are, for the most part, grossly ignorant.