The behaviours that the youth detest in elders were acceptable in the elders youth. All that changed was time. It'll happen to you, too, and you won't give a fuck what the kids are saying.
Ignorance and/or tradition are not excuses for continuing bad behavior, though.
The "acceptable" behaviors were actually wrong then just like they are now. Getting away with something bad doesn't make it not bad.
Being forgiven isn't the same as getting permission. I think we can forgive people for their past bad behavior in light of the fact that it was accepted at the time. Especially if they acknowledge it's wrong and don't continue to do it.
This argument always makes it seem like no one at the time knew these behaviours were wrong, which is obviously not true.
There is a big difference between just staying impartial and not saying anything or being an active part of whatever discrimination/inhumaneness is happening, and the people who were actively discriminating were bad people and still are.