Yes. But nothing prevents him from using it. I am sure if it helped him he would have already tried for the record with a suit. And Hall has deadlifted over 460 kg without a suit. That's about 15 lbs more than Hafthor was doing for reps. Here with Arnold looking on!
As you said - if it helped him, I'm sure he would have already tried for the record with a suit.
I would just add one small point - as you suggested, Eddie probably doesn't think the suit is helping him, so he doesn't use it. But how could a full suit not be helping him? Are suits less of an advantage as the weight goes up so high like that? If so, why? Are suits less of an advantage for extremely large lifters? Eddie appears to be wearing the bottom half of the suit in the clip above - does the bottom half offer most of the advantage?
Maybe it has something to do with the top half of the suit being so tight, and constricting his breathing in a way that makes whatever advantage it gives not worth it, thus sticking to the advantage of the bottom half alone, with more freedom of either breathing, or movement in general.
Only because world class athletes can definitely be INSANE sometimes...does anyone know if Eddie is at any real chance of death here? I have not seen too many elite strength performances that featured this much subjective maximum intensity...or absolute maximum intensity for that matter.
I fear for Eddie's health, obviously. Seems like a good bloke who I could spend several "quids" on somewhere in a UK tavern, buying him fish and chips [no idea if this makes sense, or if I may be combining Australian and UK English with a Newfoundland menu.

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I recall Vince Goodrum once reporting that a powerlifter at one of the Arnold Classic expos shat himself...even that is not necessarily as strong of evidence for top intensity, like Eddie's face bleeding, high blood pressure, etc, featured here.
Worth repeating - [1] Eddie seems like a good bloke, and [2] I fear for Eddie's health...........