"Can his joint tenant be in jeopardy? "
You don't say precisely what you mean, but even if your lender is able to go after a deficiency judgment and his interest in the PA property, that doesn't mean the co-owner owes the money. (Unless your husband's equity interest in the PA property is quite considerable, it's unlikely that a lender would go to the expense and trouble of trying to force the sale o fhis interest in that property, and depending on how they hold title, chances are they couldn't force the sale anyway -- though they could conceivably put a lien against it so that they'd get something if someone ever tried to sell or refinance it.)