I agree with that. And Traditional Catholic teaching requires that person to be Catholic.
I am a Catholic and I agree with you about being a Catholic - if we are discussing the concept of sainthood.
However, if we are discussing whether or not a confessing Christian is a martyr for the faith - if he/she refuses to renounce faith in Jesus Christ and faces death as a consequence, then that is a classic definition of the Christian martyr. It matters not whether he/she is accepted as a canonized saint. Just MHO.