To expand on the above answer, the obvious follow-on question would be "Since a mock-duel wouldn't be allowed, then why not have an actual match for the blade?" A real fight would likely satisfy honor, and it wouldn't have to be to the death, as Gideon still being alive shows. However, Bo Katan wouldn't use this option either, because even if the fight was legitimate, the story of how she gained the blade would not have the same power. Defeating Moth Gideon and earning the blade is a compelling story, one she believes she needs in order to restore her planet and people. No matter how honorable fighting and winning the blade from Din Djarin would be, that story would not hold the same near-mythic power.

To expand on the above answer, the obvious follow-on question would be "Since a mock-duel wouldn't be allowed, then why not have an actual match for the blade?" A real fight would likely satisfy honor, and it wouldn't have to be to the death, as Gideon still being alive shows. However, Bo Katan wouldn't use this option either, because even if the fight was legitimate, the story of how she gained the blade would not have the same power. Defeating Moff Gideon and earning the blade is a compelling story, one she believes she needs in order to restore her planet and people. No matter how honorable fighting and winning the blade from Din Djarin would be, that story would not hold the same near-mythic power.