Easy Street - if you look at the RNR website it states:
Q. Do all members of the Royal Naval Reserve serve at sea?
A. No, but much will depend on the job role assigned to you. Many Reservists will work ashore, rather than at sea.
So with ~3,000 RNRs then that is more than a “slack handful”. There are also Regulars that only ever serve ashore or go aboard without a role to operate the ship - does that make them a “sailor” or a passenger? Just because I go on holiday to France on a P&O ferry, and I know how to operate a fire extinguisher, doesn’t make me a sailor either!
PS. A couple of definitions from Google on Soldiers:
a person who is in an army and wearsitsuniform, especially someone who fights when there is a war:
A soldier is the man or woman who fights for their government and carries the weapons, risking their life in the process. The word comes from the Latin solidus, which is the name of the gold coin used to pay soldiers who fought in the Roman army.