I mean, he is also beating Philipsen here... Philipsen who has an even record vs Merlier in sprints this season when they have faced each other a lot.
I would not say Bini is the best, for sure, (it is probably Milan in terms of pure power and speed would be my guess) and he would not have won 3 stages if Milan and Merlier were here. BUT I think going off this season he is probably a roughly similar level and can beat Milan and Merlier depending on situation.
I actually think Merlier is the fastest sprinter itw at the moment, but I agree, Girmay is sprinting very well. I don't want to diminish his performances, but I think it is true that this is an unusually weak Tour sprint field. You have one real a-tier name, someone who has established himself as an a-tier name, and then a big chunk of b/c tier guys.
However, and maybe it's just how Milan/Merlier were winning at the Giro, where they seemed to always be a bike length+ ahead of everyone else, I think are at a higher level than Girmay. Not by much, but Girmay is also obviously a much better climber than both so it evens out. Philipsen also seems a bit off it this Tour, for whatever reason.