As opposed to a 14 year old putting words into a pig-latin translator to make his work sound semi-professional?
Sounds like what happened to me. Personally I'm not a fan and will continue calling them IG and Storm Troopers Storm Troopers. I think Astra Militarium sounds more far more "kiddy" than Imperial Guard. "Astra" isn't a problem, Militarium sounds like pig latin. I like the term Adeptus Astartes and the various Ordo names so it's nothing that I have anything against "High" (Latin) Gothic, it's just that this particular name sounds like something a 12 year pimply faced DnD kid would name his character to sound tough. Imperial Guard makes sense, the people in it "Guard" the "Imperium" vs the "Space" "Military". You can polish a turd but it's still shit.
At the end of the day, I think this is only being done so they can copyright their own names to the products. But I can't confirm that's the case.
+1 to that speculation. Unneeded I think. The term Imperial Guard has been around for years.