While I sort-of agree that it might be a dangerous practice to load .357M loads in .38 Spcl cases since they might find their way into a standard .38 gun. I also look at it this way - if we trust Guy enough to shoot a gun, why not trust him enough to have the intelligence to not let that happen. There are several ways to make an incident unlikely. Clearly marking the box of hot loads, perhaps even marking the rounds with a red Magic Marker.
As an example, I load .45 Colts for 3 different guns. The ones for my Vaquero would probably turn an SAA into a cheap bag-'o-parts. But that doesn't mean I'm only going to load relatively weak .45 Colts because that might happen. I trust myself and my procedures enough to not let it happen.