That's what I figured had happened to it, yeah.
I agree that letting him do much editing would be overpowered - but there's an obvious first step to limiting it: he can only edit (and possibly can only view) the code for things within his AOE, and if they're things which fall under the category of universal constants (e.g. gravity), any changes will be rewritten back to normal by the rest of the system once the song is over. (Also, just because he can view the code, that doesn't mean he can understand it well enough to do much editing; even if he knows Lisp, reading an unfamiliar codebase - particularly one of that scale - would be a daunting task, to say the least, especially given the very limited time involved.)
Add in the fact that he's not going to be willing to edit people, most of the time, just out of his own code of ethics - and the possible major consequences if he accidentally puts a bug in the code (this is especially bad if you don't use the "no universe-wide alterations" interpretation of the effect his AoE has on this) - and the fact that almost any edit of this nature is likely to attract the attention of the local universe's deities, who are unlikely to react positively - and I think that might bring it down to within acceptable power scales. If not, I think there are still other things which could be done to limit it... and if those aren't enough, in the end the "editing" aspect isn't a 100% necessary component; it would just be nice.
I agree that letting him do much editing would be overpowered - but there's an obvious first step to limiting it: he can only edit (and possibly can only view) the code for things within his AOE, and if they're things which fall under the category of universal constants (e.g. gravity), any changes will be rewritten back to normal by the rest of the system once the song is over. (Also, just because he can view the code, that doesn't mean he can understand it well enough to do much editing; even if he knows Lisp, reading an unfamiliar codebase - particularly one of that scale - would be a daunting task, to say the least, especially given the very limited time involved.)
Add in the fact that he's not going to be willing to edit people, most of the time, just out of his own code of ethics - and the possible major consequences if he accidentally puts a bug in the code (this is especially bad if you don't use the "no universe-wide alterations" interpretation of the effect his AoE has on this) - and the fact that almost any edit of this nature is likely to attract the attention of the local universe's deities, who are unlikely to react positively - and I think that might bring it down to within acceptable power scales. If not, I think there are still other things which could be done to limit it... and if those aren't enough, in the end the "editing" aspect isn't a 100% necessary component; it would just be nice.