It doesn't really matter if it's a diff. It matters that it was a diff that the husband apparently thought pertinent enough to mention. If it plays any part in the decision, or can show that they preferred single people in the interview, then it could be basis for a law suit (whether it would win or go to settlement is a different issue).
Nothing in the letters even hints that it played a part of the decision-making process for hiring or firing. The husband also mentioned his hair was different and he now wears glasses. Does that mean corrective vision also played a part in the process?
If the manager mentioned it, then it very well could have. Even if just on a subconscious level. I don't see anything that shows an audit of their thought processes, so you can't rule that out.
It doesn't really matter if it's a diff. It matters that it was a diff that the husband apparently thought pertinent enough to mention. If it plays any part in the decision, or can show that they preferred single people in the interview, then it could be basis for a law suit (whether it would win or go to settlement is a different issue).