Long story short. Engaged state is lengthy with a lot of effects, but most of them are referenced elsewhere in the rules without referencing Engaged state, instead of writing "engaged in CC", "in CC" or "engaged in CC Combat". Now, my counter argument to this is that this is clearly a copy-paste error where capital letter E is missing and that the rules never define what a CC (which means Close Combat) is. There's nowhere in the rules which state how a trooper becomes busy with a close combat except in the Engaged State. Their argument is that since the BS Attack against a Close Combat rule and the LoF rule provides restrictions and MODs on troopers simply by being "engaged" with a close combat, you get those restrictions even when in base contact with an Immobilised trooper. So, what say you. Does Engaged function as advertised, or are most of the rules in Engaged superfluous? Does this need an FAQ?
Just to protect from future misinterpretation. That is to say, we often think of movement stopping due to engagement; thus no engagement = no stopping on IMM/Unconscious enemies. That rule is actually tied to base contact : "A Trooper's Movement ends automatically whenever he enters Silhouette contact with an enemy, even if the specified movement route is cut short as a result."
And to be more precise, the argument is whether you can draw LOF beyond melee range when in contact with only troopers in IMM or UNC states and whether opponents still risks hitting UNC/IMM friendlies that are in contact with an enemy when shooting the enemy. You can probably translate the question as "does 'engaged in CC' mean the same as 'in the Engaged state' or can you be 'engaged in CC' without being also Engaged?"
And the rules also use a third descriptor, "in Close Combat," at least once. Under the ironically named "Other Restrictions" it says "When in Close Combat it is only possible to declare CC Attack, Dodge, Idle or Reset" - even though earlier in the same rule it already said "Any Trooper in Silhouette contact with an Allied Model that is in the Engaged State may only declare CC Attack, Dodge or other related Skills that may be used in CC." So at a minimum we have "in the Engaged state," "engaged in Close Combat," and "in Close Combat."
Guess which edition I've copy/pasted this paragraph from: If a trooper declares a BS Attack against an enemy in base to base contact with an ally, he applies a -6 MOD to his BS for each ally in that Close Combat (this is in addition to all other MODs for Range, Cover, CH: Camouflage, etc.). It's the exact same situation it was, since 2nd edition--it's all redundancies, and the rules writers not writing rules to the audience's expectation of rigor.
I thought this was solved by the fact that stopping movement, CC Attack, Burst MODs due multiple combatants etc only require Silhouette contact not to be 'engaged in CC' with the target. That is to say 'engaged in CC', 'in Close Combat' and the 'Engaged state' are all used interchangeably and are different to merely being 'in Silhouette contact'. So a Friendly model is in Silhouette contact with an IMM enemy but is not engaged in Close Combat because they are not in the Engaged state. This neatly unfucks all the issues we had with CC in late N3.