It's clear Ray and Scopper just wanted to protect their captain and Roger was using an excuse to fight Oden himself. Rayleigh can be > Oden but still seeking the help of Scooper to beat him as efficient as possible. It's like Garp and Sengoku teamed up against Shiki to eliminate the threat effectively.
Why did the whole marine HQ with a fleet admiral + 3 admirals summon the Shichibukai on top of it, just to face a single Yonko? Because 3 admirals aren't enough for an old Whitebeard? No, because they wanted to fend off the threat as effective as possible.
Ray is still labelled as a legend. With Garp putting him in the same ballpark as Whitebeard when saying we can't face both at the same time, and with Oda comparing Shanks and Rayleigh in the SBS. With Sentomaru saying he has never seen someone stopping Kizaru before, which was true for an old, rusty Rayleigh.
It's just Oda not caring about power levels and dickriding Oden.