Hmmmm. I get where you are coming from Scrape. It can be a curly conundrum. Especially in the 'physical' realm of the first three stats.
I think your query may contain the seed of a satisfying fictional-mechanical interface. If it matters how well you know someone in order to effect their attempt at something physical, then Aid/interfere is appropriate. But how?
Go back to my personal favourite principle and ask questions and use the answers...
[Astrix has failed her defy danger on DEX moving quickly to scale the cliff and so the GM makes as hard a move as they like]
GM - Well Astrix, you slip and slide precariously at the overhang, managing to save yourself from falling as you grip for sheer life, legs dangling, the contents of your pack spilling out to smash on the rocks below. But you are losing strength fast, your grip is slipping you are in danger of falling to your doom! What do you do?
Astrix - I plead despairingly back at Franz at the top of the cliff... Help Me!!
Franz - I Aid Astrix!
GM - Sure, what do you do?
Franz - I keep her eyes locked into mine as I remind her of the time she nimbly scaled the daggers of the moon with me in our youth (they have the bond - Has my back when things go wrong - and have established a childhood backstory).
GM - Nice, so what were you stealing that time? [Grins] Roll + Bond.
Franz - [7-9 result.] Later, we'll share stories later! I'm exposing myself to Danger, I'm leaning dangerously too far over to help her! I call out to Astrix: Use your feet, I remind her, don't look down! Keep looking at me! You can do it! Relax your breathing! Meanwhile I scrounge around in my pack for that elvish rope and fling an end down to her...
Astrix - I remember! I try and focus on Franz's calming words, holding on for grim death, scrabbling at the cliff with my feet to get purchase.
GM - Sounds great, you grant her a +1 Franz but if she fails, the danger is you'll be pulled over the edge too. Astrix, I do believe you are Defying the danger of falling by enduring. Roll +CON +1 for Franz's Aid. But if you fail....
OR....
Franz - I Aid Astrix!
GM - Sure, what do you do?
Franz - I throw down my elvish rope, and tell her to grab on!
GM - Hmmm, sounds more like you are Defying the Danger of Astrix falling to her death with your quick thinking, Roll + INT.
Fictionally, a very similar story is taking place, but the mechanics engage a little differently depending on how deep you dig with your questions and how willing the players are to invest in the developing narrative. It is very easy to sit shallow at the basic narrative level of the moves: This usually just involves the direct marry of trigger and narrated action, and choosing simple, direct outcomes based on the roll.
If you slow down a little, despite the frenetic or tense nature of the evolving nature of the situation, you can author the story the way you like, choosing to focus on the narrative means that 'grab' you and your players. Maybe the above scene was best served with detailing a bond a little, playing out a flashback and utilising AID, or perhaps another group would have gone the practicable Defy Danger route, or even Discern Realities.
You have an excellent grasp of the system Scrape, I really think your disconnect is nothing to worry about if you keep on following your own advice to lead with the fiction. Both ways of engaging the mechanics are fine, and I think an imaginative group could easily ascertain (with a little indulgent banter) how well a particular bond could influence a tense 'physical' situation in the story.