I agree that it's not, and never has been ok to sell off council houses (or nationalised industries, but that's another thread), but it wasn't 'morally wrong' of those who took advantage of the chance to do so. For many people, it would have been their only chance to own a home, and a refusal to do so would have been a drop in the ocean, as so many people were doing it. That doesn't make it 'right', but at a time when house prices were rising so rapidly the chance to join the much-vaunted 'home owning democracy' will have seemed much better than continuing to pay rent, particularly as many estates fell into disrepair because of the lack of rents coming in as the housing was sold.
To those with socialist leanings it was clear at the time that it was wrong, and with hindsight, it became obvious even to many of those who voted for Thatcher that the scheme was responsible for the state of the housing market now. So many young people are unable to find an affordable home, partly because there were so few new council houses built with the proceeds of the sales, partly because many were bought up as buy-to-lets and rented out on insecure tenancies at high rents. Many people bought their parents' homes with the discounts, so they inherited them when the time came, and rent them out, continuing to profit from the fact that the social housing stock was so reduced in numbers, and reducing the availability of cheaper housing in many areas.
That situation would be remedied if people who have made £££ just by living in their houses (ex-council or not) decided that it would be morally wrong to accept sums significantly higher than they paid when they also take advantage of the way the housing market was skewed and sell their homes to the next generation. How is it morally right for someone who bought a house at (on average) three times the average salary for (again on average) eight times the average salary? It would be relatively easy to come up with a formula that would value a house for sale as equivalent in real terms to the price that was paid for it, and money spent on improvements could be set against rent-free years when the mortgage was paid off. Anomalies of other types could, I'm sure, be relatively easily ironed out, too.
Would anyone saying AR was 'immoral' vote for that? Thought not.