I never said it wasn't silly. I said that would be the aiki approach (and the approach in some Aikido schools). That's why there have to be less-aiki tools.Not sure what you mean by the other guys lean Both guys are pretty much centered. The grip fighting is in effect static vs static. It is in part either to gain a control or create a response. It could be done from an upright position just you are more easily taken down that way so wrestlers dont do it. This is because you need your hands near your legs to defend takedowns.
You asked for a situation where someone would do a static arm grab attack.
All of wrestling is one of those curcumstances. This transfers in concept of fighting in that the arm grabs then stop weapons and punches. So you may employ this or even face it on the street.
Waiting for something to happen is silly. Something has happend. Your arm has been grabbed.