NLR will apply if someone gives you an order, and as a result of not following that order, you are killed, the same as before.
If someone says don't revive Joe or die, and a medic revives Joe, and the medic is killed, NLR applies, the medic can't go back because he was killed legally.
Being accidentally killed is very vague in this instance, and so it's situational.
Was he killed accidentally in a head-on collision with a civ? Yes, NLR applies. Punishment can occur if a medic goes back.
Killed accidentally, and it can be considered RDM? No NLR will not apply. No punishment for going back.
It is difficult to list out all the ways you can be accidentally killed, if there are any specific questions about specific scenarios, please talk to mods/admins about what classifies as RDM, VMD, or an Arma bug and what will not, you can also come to speak with Sr.R&R, and we will do our best to assist you.
This confusion around the word 'accidental' is ultimately why we decided to remove the word and consolidate all NLR to the one chapter.
I am not sure what part is contradicting itself; the red part is removed because the verbiage "accidentally killed" was being used to expand the exemptions of NLR. The 'accidental' contradicted chapter 14 where it is explicitly stated that NLR exempt scenarios are RDM, VDM, and Arma bug, that is why the section with 'accidental' was removed, its an effort to reduce confusion and contradiction.
Ultimately the whole chapter boils down to NLR applies in all situations except the explicitly stated exemptions RDM, VDM, and Arma bug. If it's not one of those three things NLR applies, the handbook update was to try and clarify that.