It’s certainly possible that such voting “restrictions” may end up blowing up in the Republicans’ faces. Just look at how Democrats exploited the runoff system in the state - which had originally been instituted to favor white candidates over black candidates - to pick off two Republican-held Senate seats, sending their first Black Democrat to the Senate in the process.
David Perdue's whiny complaints that in any of the other 49 states he would've won on election day (Louisiana, California, and Washington beg to differ but whatever) is not wrong, but when you set up bespoke rules, don't be surprised when the other party starts rules lawyering you.