Divorce is not always a sin; it results from a variety of causes; and it is never held up as an example for kids to follow or taught to be in any way equal to non-divorce. It is acknowledged by all to be a failure. If Dale would like to acknowledge his immorality and change his ways then I imagine the BSA would reconsider.
A speeding ticket? There is a legal punishment for that, and the leader, I am sure, would freely tell the kids that he was wrong.
Your examples are apples and oranges. Gayness is a behavior that should not be held up as a positive example for children. Drunkeness, divorce, and speeding maintain their low moral status already.
A leader can be banned for any of these things, or for any other reason, by the unit's sponsoring institution.
Here's an extreme example. A physician who is an abortion provider applies to a unit to become a Scoutmaster. If the sponsor is a Roman Catholic parish, they'd probably say no. If the sponsor is a public school, they might well say yes. It's up to the sponsor.
The determination of whether or not someone is moral enough to be a Scouter is in some very limited cases set by National. In other cases, it's left to the sponsor.