First off, I'm not an AW expert by any means. My first (and so far only) attempt to MC the game failed miserably, so it's advisable to take a lot of sat with what I say. :)
It seems to me that everything you said in the previous post is correct. When a character with Leadership uses their gang to do something, the player should probably make a Basic Move. But I think the important part is the second paragraph of the Leadership move on pg. 226.
When the gang is fighting but the hardholder doesn't spend hold, they fight conservatively, for their own survival, or else they fight according to their impulse as a threat.
The section called Gangs and fronts on pg. 253 notes that when a gang is present, it'll either be listed as an entirely new threat, combined with an existing threat, or be listed on the home front. Vincent notes that gangs will usually be some flavor of Brute (unless they're a really weird gang, I suppose) and they'll have an appropriate threat impulse.
So if, for example, the gang is denoted as being a Brute: Family (impulse: to close ranks, protect their own) and the hardholder doesn't spend any hold, I could see the MC narrating how "Oh shit. Plover's been hit. He's down. III and Churchhead run over laying down suppressive fire, standing over his body. Isle scampers towards them, dropping her gun as she clamps her hands over Plover's wound. She's screaming for an angel. Plover's coughing up blood and jerking like an electric current's going through him. What do you do?" Now, instead of doing whatever it was the hardholder's player wanted them to do, they're acting on impulse; protecting their own. They're standing there in a little knot over the body of their wounded gang member with bullets whizzing all around them when they should probably just leave his ass and find some cover.
I think the other important thing to note is the Leadership move specifically says "when your gang fights
for you". Not just "when you make them do something". It seems that the hardholder's gang is naturally more disciplined than the chopper's bikers are. So I think your stand sentry, put the hurt on, and lay in ambush examples are spot on; the gang's not really fighting. They're also not really acting in a way that goes against self-interest. "Stand sentry? Sure. My ass doesn't want to get sniped." "Go collect a debt? It's what? 5 of us against a single dude? OK." "Keep my head down so I don't blow the whole ambush and get myself killed? Hells yes."
Basically, I think the hold from the leadership move represents the hardholder getting their gang to do something even if they wouldn't normally do it. Unlike weapons and gear, gangs are people, have their own agency, and don't want to get hurt or killed. Spending a hold means you sort of suppress that, force them to hold their shit together, and act against instinct.
No hold spent example.
Hardholder: Go take that heavily fortified bunker!
Gang: What?! Half of us will die getting to it. Fuck that.
At this point, I suppose that the player could Go Aggro on a few of the gang members or maybe Manipulate them, but do you have time for that? If a few of the members choose to suck it up, are you really going to inflict harm on them? Right here in front of everyone with the enemy shooting at you? Do you even have any leverage to Manipulate them? All of them?
So when shit gets real (i.e. there's a serious chance people could die), I think the MC is will within their rights to *not* have a gang comply with the hardholder's order if they don't spend hold. That's what the leadership move does.