Interesting wording in the law. The way it is written could be argued both ways. It doesn't say write ins are forbidden in the primary. It says that write ins are accepted for elections, except for primaries.
At any rate, if the majority of voters write in a candidate that beats the person “deemed” to have qualified, a good case exists for a legal challenge based on disenfranchisement of those voters. Voter's rights have been found to trump rules.
That would be a fascinating outcome. Myth gets 25%, RuPaul gets about 10%, and the remaining 65% goes to "unaccepted write-ins".
It depends on how the voting machines are set up. If there’s no “write-in” option at the machines, then there’s no write-in option. Even if there were a write-in option, it would require a massive communication effort because the poll workers probably will do nothing to encourage write-ins.