Gergely Orosz provides helpful advice on a difficult situation. I will add that you can take the different concerns and address it in the onboarding plan (probably needs to be more tailored), who will assist with it, and how to measure their success after 30 days, 90 days, and 180 days. Remind the team that you'll own the decision for better or worse, and need their support and trust if we want to give it a real chance.
Hierarchical hiring decisions vs peer hiring decisions is an eternal balance. If you hire hierarchically, managers may be fearful of hiring people smarter than them or more experienced than them. If you hire based on peer voting, you could fall into a vapid paper-clip-maximizing monoculture.