Not impossible to do without a cheat program. You give no details as to the number of rounds played and the conditions of said rounds. Additionally there is no indications of how many thousands of attempts were aborted before the last hole until the player had the overall score he/she was willing to post.
I would imaging it is most likely someone who is cheating but not necessarily using a program. A legend with legend skills can easily set up a 2nd account in violation of the TOS, level up without "tiering" up, buy or gift himself the top equipment. Find a tourney or set up a game with easy conditions and fire away with legend skills, knowledge and equipment from short tees. Don't actually finish a round if the score at the end of 9 holes isn't going to be a 25 or 26. Just keep dropping out of the solo round and start over as needed to accomplish that goal.
If the person is actually taking credits from people in competition, turn them in to WGTIcon for further investigation. If it appears that the person is merely playing solo games to boost his/her ego, what harm are they? Those are the types of players who go through tons of credits in balls and equipment and help keep this place free for the rest of us. Think of how much worse the advertising would be without them.