Go for the kneepads if you need them (or want them). If your sensei says its fine, give it a go. Some places (budo aoi) sell kneepads for iaido, but I imagine volleyball pads would work too. You can always get a pair, take them home and try them out. If they don't work, return them. I wouldn't try them out at the dojo unless you are going to keep them if they don't work out. No need to return sweaty ucky kneepads.
.......Just try to remember that when someone talk their reasons why they don't bow to shomen. @Janet @Mary.
Was there a reason to have that here? Just curious, as I don't see how it benefits the person who asked the question. No need to drag drama from another thread into this one.