> "Access to all other modes of transport other than foot is implicitly "no", " is weak as "implicitly" falls well short of "no"

No, "implicitly" here means "no, unless some other tag such as bicycle=yes is present".  On e.g. the highway=footway https://www.openstreetmap.org/way/23641643/history no such tag is present, so "access=no" is redundant - the sorts of traffic allowed on this footpath would be exactly the same whether or not the "access=no" tag was preent.
