Everything anyone says is an "opinion" according to some definitions of "opinion." The distinction here is whether something is a claim of fact or simply a claim. A claim of fact is something that can be verified through some sort of objective measurement or detection.

"Some pigs fly," "Bill Johnson signed over his rights to the song," and "This fish is 3 pounds, 4 ounces" are claims of fact.

"Some pigs are beautiful," "Bill Johnson writes too many songs," and "People who catch fish are probably the same type of people who support terrorists" are just claims.