in virginia is my stepfather liable for a judgement on property his deceased wife had

A spouse is not automatically responsible or liable for all debts of a deceased spouse--he is only responsible for debts he co-signed or guaranteed or for certain expenses for "necessary" expenses like non-elective medical care (because the law requires spouses to help take basic care of each other). This is not a necessary debt or expense, so as long as your stepfather is not on the debt, did not guaranty it, etc. he would not be liable.
However, your mother's estate--the property or assets she left behind--may be liable. So, for example, someone owed money in regards to the campground could try to recover money from, for example, a bank account of hers. Or if there is a lien on the property, it cannot be sold without paying the lien (e.g. at closing), which will reduce the proceeds from the property. This could potentially reduce the money your stepfather will inherit from your mother, but that's the most it could do: he will not have to pay out of pocket, and will not have a judgment against him.
Don't listen to the lawyer's threats: if he thinks he has a valid case against your mother's estate, let him file it, then you (or whoever is the estate's executor or personal representative, on behalf of the estate) can respond to it IF it occurs. Neither you nor your stepfather should pay anything out of pocket.