Your argument is based ignoring all factors other than the string. If you want to do that, you have to first prove that all other factors are literally silent ones, or that they are impossible to detect.
No, I don't have to do any such thing to address the question OF THE OP.
The problem here is that you are talking about all kinds of other things extraneous to the question. There is a huge variety of approaches to the key possible in both staccato and legato playing. There can be huge differences in weight, acceleration, key thump and whatever else you want to bring into it. Since those things are VARIABLES in BOTH cases, it's completely ridiculous to try and squeeze them into this argument as if they are constants affecting THE LEGATO in a predictable way that we can then compare.
You can play staccato with greater key thump than legato, and YOU CAN ALSO PLAY LEGATO WITH GREATER KEY THUMP THAN STACCATO. The OP didn't say anything about what dynamic he was talking about, what kind of arm weight or anything else. In fact he's since clarified that he wasn't even referring to staccato (let alone "pizzicato"), he was only referring to "non-legato".
The ONLY variable that the OP specified, and thus the only thing we are comparing here, is whether the keys, after being played, are held until the next keypress or not. All of the other stuff you insist on introducing here is just a mass of irrelevance. If you want to compare the effects of various specific actions, then we can do that. But it's another thread. This one is about legato.
How long you hold the key down after striking it makes no difference to the sound when the pedal is down. That is a simple acoustic and mechanical fact. It's a fact completely separate from what's involved in striking the key in the first place.