I'm not making blind assumptions, saying it's bulls*** and then saying that what I've said can be used against every non logia user is supposed to make what I said any less true? Tell me of a dude who's defeated someone faster and with more damage output than himself and then I'll tell you that it's true,I'm being simplistic!
Instead of going all that way to say I've said momonga is the coolest thing since sliced bread,just put a blade in luffy's hand,some control over it,and make him fight Magellan again, can you honestly say that Magellan'd win forsure? The sword would just raise luffy's damage output,going from seriously hurtful,to deadly! But it's just not luffy's kind of style, I know that if every character did the same thing,just add a pierce weapon to their arsenal,the story'd be dull,but guess what? there's swordsman who've been introduced, so that does exist, there are characters with a weapon that can kill when pierced by it, so that makes my theory plausible about Magellan not being suited for an admiral!
Now do the exact same thing that I told you to do with luffy and get him to face an admiral,by pure facts alone,could he defeat anyone of them? no he couldn't! add Haki to the equation,could he? No,he couldn't, all the admirals got haki,they can prefict ones movements to some point, hell! Aokiji got pierced by WBs bisento,and I think it's safe to assume WB's gotta be one of the best haki users around and he didn't get hurt,put magellan in his place,would Magellan be around standing?
Like it or not,it's true, simplistic logic or not,it IS true, Magellan does not have enough defensive versitality to be an admiral, and I used the Momonga reference because he apparently knows that same technique Lucci used (not sure of the name,so I won't try to spell it), so that does make him at least equal in speed to luffy, now instead of brute force,he uses a sword, replace luffy's fight at ID against magellan with a fight beetwen Momonga and Magellan,and let's not forget Momonga does know haki,so better perception of the opponents attacks, replace any attack luffy used on Magellan for a sword's pierce,can you honestly say Magellan'd be alive? no,you can't, can you honestly say momonga would be alive? you really can't. Now do the exact same thing with Momonga against any of the current admirals, can you say that Momonga would leave that place alive? he probably wouldn't,would any of the admirals? they probably would.
Get my point? Magellan's not on the admiral level,not by a long shot..