Meaning neither Shanks nor BM or Roger are swordsmen if they doesn't consider themselves one
Zoro's Statement isn't so that you claim People whose entire Fighting Style revolves around their Sword aren't Swordsmen,
It's so that We also include those who don't have Swords or have Fake Swordsmanship yet call themselves Swordsmen,
Such as a Giraffe who consider his Legs Swordsmanship or S-Hawk who turns his Body into Blades or Ohm who has a Transforming Whip ... etc
Zoro isn't "Limiting" his Targets with that Statement, He is Including More,
And I already mentioned how both Zoro & Cabaji don't consider Dirty Tactics to be Part of Swordsmanship, yet Cabaji considers himself a Swordsman & that's enough Reason for Zoro to teach him a Lesson even if He is not Fighting Fairly,
Those who are Swordsmen are Clear, you don't need to hear it from them, Shanks & Roger are Swordsmen whether you Like it or not,
But those who call themselves Swordsmen even though They are Fighting with their Legs or Circus Toys or Fake Sword are also Welcome as Mihawk/Zoro Victims,