I've tried putting it in initIntro.sqf - but it seems to never get executed at all
Odd, just tested this myself and it seems to get executed just fine, as long as you preview it in the intro "section".
It also nicely prevented the soldiers from speaking to each other..
My magnificent intro was constructed so that dude1 was standing alone and then dude2 walks to him (previewed via player), no camera scripting involved..
The initIntro.sqf contains:
enableRadio false;
{_x disableConversation true} forEach [dude1,dude2,player];
{_x setVariable ["BIS_noCoreConversations", true]} forEach [dude1,dude2,player];
There however seems to be a weird bug in the game regarding this:
If I let those two guys speak in one preview, then add that stuff into the initIntro and preview again the global radio output text of what they said to each other on the previous run is displayed from the second the intro starts regardless of what enableRadio is set to (and the guys of course won't speak to each other)..