Well, I wouldn't actually ignore it. Or do I mean "couldn't"?
What I think is that you should fit the parts in the order stated in the instructions which is the order SU fitted them when they assembled the carbs in the first place: ferule, washer, gland, sleeve nut, as they go down the hole.
It would be nice to hear from others who've taken apart ones that were untouched since manufacture, but I'm sure of the order SU fitted the parts.
And the point of the story about the aircraft engine seals being packed in a different order than assembly required, is that you can't rely on it even in such safety critical applications, where failure condition severity is catastrophic.
As to the technicalities, I do wonder, if the gland goes in before the washer, what's to stop it oozing into the bottom of the chamber between the orifice wall and the tube if the rubber softens. The innermost, bottom most edge of that orifice is only a casting in zinc aluminium alloy. So control of its exact dimensions won't be great - it's a nice casting, and well good enough to hold the flange on the inner end of the ferule in the orifice, and so hold the tube back. But there could be some variation in the gap between the plastic jet tube or ferule flange and the bottom hole in the orifice, casting faults, possibly even damage from disassembly by the ham-fisted.
Whereas, the part of the orifice where the threads for the sleeve nut are cut and the ledge at the bottom of that part of the hole are machined. So their dimensions and tolerances are controlled; as are those of the metal washer and the inner face of the sleeve nut, which should be new every time you fit a new jet. So, if the washer goes in first, it bares on that machined ledge and can be guaranteed to fill the whole of the gap between it and the plastic tube, which is supported by the inner ferule. So, the washer fully holds the gland in compression against the plastic tube, and it's going nowhere unless the packing gland entirely liquifies. Even if it starts to turn to jelly, the packing gland can't easily get out of the stuffing box that is formed anew each time by the inner face of the sleeve nut and the washer.
As to whether there's a need for a washer between the face of the sleeve nut and the gland: clearly there isn't. That the gland is not damaged by the nice new inner face of the sleeve nut is shown by the simple, plain impression of its face on the gland in the previous picture of one (I'm sure) SU assembled. If it was intended that seal would be frequently dissembled and re-assembled with the old parts, that might be a different issue. But baring having to replace the float chamber, I can't see a reason to do that often.
That washer, rubber gland, sleeve nut combination does sound a better solution than the olives, in some ways. And looking at the surround to the inner hole in the orifice, it looks to me like it was meant to take an olive, and the rubber gland was a design improvement (though there may be several reasons for such changes; Microsoft change stuff just because they can). Except, I don't feel I can predict what's going to happen with fuel compositions in the next 10 years or so. In which case, choosing a rubber gland that will be good for that long is a guess - and someone else's to boot.
Whereas, if the olives seal without the sleeve nuts stripping, as they have, I reckon they will be set for life (mine at least). And not in the sense of the wristwatch with the lifetime guarantee - when the mainspring breaks, it slashes your wrist. Though I admit I was worried that they wouldn't seal and wouldn't have tried if I didn't have a spare set of float chambers. So I was a bit concerned when the first attempt failed. But that was carelessness on my part in the assembly, not a fault in the implementation.
But the bottom line is this: The instructions say take note of the ferule, washer, gland, and sleeve nut - I assume meaning take note of the order they come out - and put the new ones back the same way. So if you are replacing an original jet tube seal set that was fitted by SU and you follow that simple rule, you won't have a problem or be confused by what's been written here. But if you are replacing a replacement, be aware of what it says in the instructions about that order they go down the hole - ferule, washer, (rubber) gland, sleeve nut.
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.
Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).