This is what I figured out.
Two possibilities, that each of them may hold the truth or maybe a combination of them.
1) If they see Skullknight overcome Griffith, Skullknight will take Griffith's majestic figure importance on people's minds while he is also something astral and this will lead to even more new era's phenomena (see Qliporth) and more demon aka Godhand, as what they represent, power. So Skullknight's best bet is that a human defeats Griffith so that everybody can see and thus make demons lose their legendary status importance.
2)If again people don't see skullknight overcome Griffith, Griffith won't have an assasin on people's minds and Griffith will continue to have its legendary importance status(propablly turning to be Phemto).
On a few words Skullknight wants to humiliate Griffith, a demon or his power and thus what he represents by someone human, someone representing human status.
So Skullknight wants to take advantage of the situation Griffith is on earth to use the humiliation plan on people's minds, that will hurt Godhand.
Two possibilities, that each of them may hold the truth or maybe a combination of them.
1) If they see Skullknight overcome Griffith, Skullknight will take Griffith's majestic figure importance on people's minds while he is also something astral and this will lead to even more new era's phenomena (see Qliporth) and more demon aka Godhand, as what they represent, power. So Skullknight's best bet is that a human defeats Griffith so that everybody can see and thus make demons lose their legendary status importance.
2)If again people don't see skullknight overcome Griffith, Griffith won't have an assasin on people's minds and Griffith will continue to have its legendary importance status(propablly turning to be Phemto).
On a few words Skullknight wants to humiliate Griffith, a demon or his power and thus what he represents by someone human, someone representing human status.
So Skullknight wants to take advantage of the situation Griffith is on earth to use the humiliation plan on people's minds, that will hurt Godhand.