Who the fuck cares if Garp was in some silhouettes or not?
His hype is tied to Roger himself, not some Fucking silhouettes that Kaido sees.
- Roger said that they fought each other multiple times, that they pushed each other extremely far.
- Garp/Roger defeated Rocks, again, portraying Roger/Garp as equals.
Garp is stronger than Kaido based on his own hype, this doesn't even need to be said, but oh well.