I had to sign for a GOP ballot in Michigan so there is a record and democrats who crossed the line “shouldn’t” be able to cross back to vote for a democrat in the event of a revote.
Personally, I think they should be able to do it. If there are revotes in these states, then Hillary is the nominee unless perchance the Dems who voted in the GOP primary because the Dem primary did not count are allowed to revote.
Once you change the rules in the middle of the game, you’ve got to make allowances for the unfairness caused by your original rule.
Obama needs to press the DNC on that issue. Otherwise, he’s pretty much handing the nomination over to Hillary.
The big problem, though, is that you don’t know which of the crossover GOP voters are there because they truly support the Dem, and which are there because they just want to vote for the weakest Dem.