You cannot have read my posts or seen the picture. Like I repeatedly have written, the AFOV or TFOV does not change from collapsing or extending the eyecups - as long as you see the field stop and no kidney beaning occurs.
However, when the bins are used in front of the eyes, there is more than the actual image in the bins. When the eyecups are extended, for example if that's how you prefer to use them, or because you need to keep sidelight away from the oculars or any other reason, they physically form a tunnel.
The inner edges of the eyecup, that of course form this tube or tunnel, obscure YOUR visual field, that exceeds 180 degrees if you're healthy.
First comes the image, then comes the rim around the oculars (which can be thinner or wider because of the construction, the ocular lens size and the setting of the eyecup), then comes your hands (roof prism) or the prism housings + your hands (porro).
You may know that I have the Fury 6.5x32 in my possession, and it gives an excessively different feeling when used with the eyecups extended compared to when they are down - much more different than other bins I have tried.