There is no confusion about this rule, nor has there ever been, amongst more experienced players. The people responding in the thread are probably feeling frustrated by what seem to be attempts to select pieces out of a single rule rather than take it as a whole. That's the feeling I get, but it's for them to say.
If you are briefing your squad about conventions normally in use here's a bunch:
You can use the ride you were issued with to shoot with at any target, but you cannot use a ground, ship gun or chute pistol (on the ground) unless specifically stated that you can do so in the frame rules.
You can "join" another player and gun for him or just travel with him as a lookout and criticise his flying as you will.
You can vulch people on the rearm pad.
Killshooter is usually off. Shooting friendly forces or objects deliberately is forbidden.
Using channel 200 is forbidden.
If you want to speak to a CM they lurk on Ch202.
If you disco or crash in the first 15 minutes, before contacting the enemy, you can reup without asking.
If you have more players than you are supposed to have (more than 2 over) they can be "farmed" out to a squad that is short without prior arrangement, or they can simply "join" another player.
If CICs agree to end a frame early and it is so announced, then that's it, game over. No chasing down somebody returning home or trying to disengage.
If you get the opposition game plan by accident, just delete it without reading it. This stuff happens, no big deal.
If you suspect that something has happened that is not quite "according to Hoyle" then use the private channels to take it up with an appropriate CM in the first instance.
There's probably more but they are the topics I see most queried by the young and restless.
In FSO, it is attitude that is the big difference from the MA, not gameplay. As it is a squad event, discipline and education are necessary at the squad level for the FSO attitude to prevail. If you want a rule clarified and a CM has clarified it then it's usually best to take it off the boards and harass them privately until you understand it.