Bad showings can be even against similar level opponents, there is no rule lol.
And in fact those are better than against vastly weaker opponents for obvious reasons.
And for the fourth time, what deterred Aramaki, by his own words, wasn't Shanks alone but all RHP

. Meaning he was pretty ok with facing Shanks.
But again for the fourth time, if a similar haki got 4 Gorosei de transformed, then yes, what's the problem if when cheapshotting Aramaki alone he was de-transformed?
The asks GB why only all the RHP were the issue, and why "it wasn't the time".
I'm not arguing he would win against Shanks: I am saying he wasn't deterred by Shanks alone, and that's explicit.
Ok, so what's the problem for Aramaki who looked much better in "1vs1"?