The recent Skeptical Enquirer article linked to this site proclaiming antimatter propulsion as “pseudoscience” was.….wrong.
Antimatter will have to be produced in quantity to be used for propulsion but very small quantities may be all that is required for an interim system using antimatter to ignite fusion reactions.
It may be that some people pushing their own miracle solutions do not like other more practical possibilities.
Unlike any type of gravity manipulation, anti-matter is a fact. Anti-matter catalyzed fusion is a possible method of interstellar propulsion; far more in the realm of possibility than anti-gravity.