I think that is the completely wrong approach. The issue at hand is so important that we can't allow ourselves to create the smallest hint of a barrier that could deter people from coming over to our side.

It means not saying "I told you so" when someone comes to you with a 'revelation' that you specifically warned them about 6 months prior (I have personal experience with this situation). It means we have to welcome everyone with open arms, no matter what they've said before. For the sake of everyone, we have to put our egos aside, however hard it may be.

In the future, when the threat is truly over, we can have the discussion about how we prevent this type of thing from ever happening again.