If this is really true, it is a very important improvment : it means that the fork will be softer in compression as the air chamber will not be closed anymore. When I changed the OEM springs for Wilbers progressive springs, I also increased the air chamber size, by removing some oil, and this has softened the fork in compression.Oh, and a little vent screw to burp the air that gets squeezed out of the fork oil (I guess)..
For sure ! If the fork is opened at its top, it means that the air and oil within the fork will not be compressed at all, when the fork goes down.I believe that they should not be left open. They are used to only settle the ride height once the forks have been pumped up and down a few times and then closed. This allows the oil quantity and air gap to be fixed to the damping specification you want to achieve. My 1974 GT750 had these fitted!!