I don't think you are over-reacting.
Not because the barber may be breaking the rules, as rules do not protect anyone from the virus - behaviour does - but because because as a couple you are in this together. If one of you behaves in such a way as to risk contracting the virus it has an impact on the other.
For this reason, I think your husband was out of line. Having said that, given that you are going out to work in a shop once a week, I think you are also taking a risk which could affect your husband, so maybe you need to work out between you where your collective boundaries lie?