Because you suck and we hate you
No surprise that H undh K doesn’t want to sell it’s uber tacticool, wizbang odd-calibered personal defense weapon. After all, they shit on the civilian market a lot. But when a magazine that pimps guns to gun people agrees with them that civilians shouldn’t own this gun, that’s stupid. Instead of sucking up to the HK rep and pull a Zumbo, ask them why they think I can’t own a small caliber gun that (being an HK) probably has a shitty trigger?
Also, H undh K has no problem with this gun in movies.
The ironic thing is that, thanks to the vagaries of 922(r) requirements, a semiauto MP7 clone here would be dumb, awkward, overpriced and just generally turn into eventual CDNN fodder* in the same fashion as the import-neutered G36 variant, the SL8.