You cannot (officially) be df'd for associating with DF'd - especially when it was an urgent and extremely private financial/business matter which it was of course!
But ... there is the "catch all" brazen conduct and causing divisions which can be wheeled out by zealot elders to back up their action by stating you are disturbing the peace of the congregation. You will also get stick for publicly meeting and eating with said df'd person.
If you want to tell'em to do one and take the consequences of shunning and initial loneliness (it can hit you like a ton of wet sand especially if you haven't really prepared for it) then fine but if you want to play the long game then DO NOT MEET WITH THEM and tell any enquirer you are not prepared to discuss "a private financial/business" meeting under any circumstances. You might also be a little contrite and say yes maybe I shouldn't have met in public but It needed to be done.
Any twinges of guilt can be suppressed by remembering you are playing the theocratic warfare game back at them.
Best wishes.