That's certainly a possibility, but there are a few limiting factors as to why we probably haven't seen a public one so far.
Difficult to code. As you said there are few things harder to code than something as dynamic, complex, and skill-intensive than The Gauntlet/Corrupted Gauntlet. This means there's not many scripters who would be even capable of writing a script like this.
High requirements. The Gauntlet of course requires the Song of the Elves quest line to be done along with good stats. This means there's not a lot of people who even have accounts that could run the script, and if an account got banned it would be hundreds of hours to put into a new account to get the requirements for it.
Low return on investment. Because few people would even have accounts to run a script like this, not many people would likely buy it. So either the price would have to be extremely high or else it wouldn't make much money due to low sales.
With all that in mind, there certainly are Gauntlet scripts out there somewhere. If you stand outside The Gauntlet long enough you'll see accounts with minimum requirements for The Gauntlet and high KC with pretty much no other boss kills. The reason these scripts are probably kept private is for the reasons stated above. You could make a ton of money if you had just ~10 accounts running a script like this, so they likely make far more money from selling the gold and staying under the radar with low bans than they would selling the script publicly to a rather small customer pool and risking getting their script more attention and increasing bans.
Even still, it's possible one of the very talented scripters on OSBot or another forum could put in the time to creating a public one in the future.