Can imagine Ra's and John meeting the high table adjudicator:
"So I said 'You want me to kill John Wick for killing a high table member. Who only got that position by forcing John Wick to murder a high table menber using a marker, of which he was bound to obey on threat of being killed.'".
"And that's why we're fighting to the death?"
"Oh heavens no, I cut her down right there and went on to slaughter the high table. Bunch of incompetents like that is bad for the worls terrorist organization business. I just want you to take over as Demonhead, and we must fight to the death to consecrate the ceremony."
"Alrighty then."
Wick is inferior in pretty much every physical stat, especially strength. Ra's would manhandle Wick barehanded. Reminder that in h2h he outright beat Batman even though Batman was heavily armoured. Ra's could hurt him through the suit. And in general could match strength with a guy who can curl a two hundred or more pound man (in this case Ra's himself) with one arm in a compromised position.