To ask the question is to already know the answer.
This particular ballot won't move the needle for anyone who has already decided what they believe. It's a single ballot, and if you're being honest with yourself it pretty clearly looks like the voter scribbled out a mark for Trump and voted Biden because every other mark on the ballot was identical to the Biden mark, not the trump mark.
Of course if you're being honest about what a vote adjudicator is supposed to do, the instructions clearly state "so not make a check mark, fill in the circle completely", and the only circle completely filled in on the entire ballot is for Trump, so the question isn't "is this a trump voter" as much as " this ballot wasn't filled out correctly, does that mean it gets thrown out, do we look past the voter's inability to follow directions, or does it mean the accidental vote for Trump counts?"
whatever you think, the rules should have been established publicly before the election, and adhered to strictly and consistently across the state. That's what fair is.
I vote via Georgia Absentee ballot in every election. It’s not like hanging chads. You’d have to have a major case of Parkinson’s disease to mark something by mistake. It sounds more like they couldn’t scan the ballot for some reason so they have to count it manually. The only way you could really cheat on it is by either willfully miscounting or filling in a choice that was left blank. A willful miscount would be easy to spot in a recount and I doubt there would be enough blank choices to sway anything larger than a local election where a vote or 2 could make the difference.