I understand that you're hiring a contractor. I suppose you want someone who is going to be able to hit the ground running? Still, I'm not sure you're maximizing EV with this requirement. You're excluding many, many skilled devs who would be highly motivated to make a difference working on your team.
Learning a new language and framework, likely very similar to one or two they already know, is not considered a major hurdle in most of the private sector. Especially at this band of compensation.