In that particular case? First, because it was the best avenue of advance (best payoff, least number of orders, juiciest targets, etc.). Second, because a Rafiq sprayed the SAS off of the Maggy in the following order using Triangulated Fire. It's easy for a player to engineer a situation where a TAG has to pass within 2-4" of a camo marker (with respect to units with Kinematica) in order to cover its ideal route of advance. It won't happy every time, but that's what Engage is mainly used for in my games - tying up a unit that will either attack my unit with a DTW, or tying up a unit that probably has a poor chance to win the Engage FTF roll using a normal BS weapon.
Oh, no I meant adding that as an ability for Engage or CC: like, Symbiomates can't block CC, or at least Assault/Berserk attacks. Something like that. I just hate that they're such a clutch-heal already...
Although I think it would be crazy to modify again the SymbioMate rules, your proposal is very good because it gives more choices and counterplay, without making the SymbioMates bad (in fact, they would remain incredibly good for their cost). Also, it reminds me of Dune (completly stops fast things, doesn't stop slow things).
Honestly, even if we accept that Engage is supposed to be very situational, its "bug" with wall placement should go. The easiest way to do it is to remove that "opponent places your model" thingie. As for "CC specialist being oppressive in buildings" argument: unless by "building" you mean "strategically important countryside toilet" that can barely fit 2 models, this issue can still be solved by 2 mooks and 2 orders since it's still an active player who decides where to place that base which defines where exactly the engaged model can be placed "in base contact". Still, I don't quite understand why should an option already very situational due to having almost unrealistic (most of the time) requirements be still bad, if not worst, even on a CC specialist in a shooting game, even when said CC specialist can actually, once in a blue moon, try to declare it.
Good news! Everyone should play Infinity with CC focused troops on the 31st, as there is an actual Blue Moon on that day. Rejoice in the ability of your opponent to lock your specialist in b2b with a mook while the rest of their force waltzes on by.
Um... I don't think an ability to Engage a specialist with a random mook is something that will see a noticeable change if CC specialists specifically receive a buff to their ability to Engage. Unless said mook is an expendable CC-oriented WB or something. Even then, we are talking about reactive-turn-only ability. If your specialist is getting Engaged on his active turn, it means it's you who decided to take chances for some reason because it's you who has almost complete control over applicability of said 2-4 inch range ability. That said, current Engage kinda makes perfect sense - it's basically RAW for Dodging into B2B, except it's "homing" to actually end up in B2B by the end of the Order, no more and no less. It's the clause about model placement that's out of place with this line of thinking, actually.
While I think that removing the opponent-places clause would make sense as it is the wrong compromise in the situation where two models move simultaneously, I still think Engage will for non-Pupniks remain wasted forest to even put the rule to print (or wasted uranium for the digital PDF/wiki search). It would make the most sense if the movement would have to follow the same movement rules as for Guts Roll (i.e. enforcing the general movement rules and limiting it to what the trooper is capable of with a Short Movement Skill) and a Trooper that finds itself getting Engaged by an O-Yoroi could use a second Move skill to get into f.ex. the Armoury to cause the Engage declaration to simply fail.
My post was a tongue-in-cheek response to the post I quoted. The implied message being, "sure, you can engage my mook that I moved near your CC specialist because the opportunity to do so finally presented itself on January 31st (when a blue moon will actually happen), but why the hell would you want to actually do that?!" Edit: I see why it was confusing! I used "your" instead of "their". Fixed :P.