A Strict Fusion Summon is a Fusion Summon that can only be conducted with the Fusion Material Monsters listed upon the card. As such, Fusion-Substitute Monsters such as "King of the Swamp" cannot be used as Fusion Material Monsters. Furthermore, these monsters cannot be Summoned with "Instant Fusion".
However, using a card that changes its name to that of a correct Fusion Material Monster, such as "Elemental HERO Prisma" or "Phantom of Chaos", that monster can be used as a Fusion Material.
The Condition of being a Strict Fusion Summon Monster does not have effect on being a Nomi Monster, or vice-versa.