You make some good points about the local talent angle and the future.
In my opinion, this industry is beginning to move away slightly from the "only M rated titles sell" myth. Nintendo is the leader in this, obviously. Mario Kart Wii was the biggest mover of software units in 08 according to NPD. EA is beginning to follow suit saying that they are now going to devote more of their resources to dev and pub for the Wii. I believe a developer can be successful and not do M rated titles. They just have to be quality games.
If I were in the House or Senate, I would vote for the bill since it has no upfront costs. However, I am skeptical of it's impact.
Personally, I am not concerned about the M rated games thing either as I have no plans to make any ever. But there are a lot of developers that make a variety of games and if they have any M rated games in their development pipeline, that will make Oklahoma less profitable than other states that offer tax incentives without ratings restrictions.
There is also the minor concern that someone making a game and shooting for a T rating can theoretically add a little too much blood or something and push them over the edge into an M rating. It wasn't intentional but it happened. If they for some reason can't appeal the rating or are unable to to spare the time and resources to edit the game, they will no longer be able to apply for tax rebates for the game although they were planning on it at the beginning of the project..
Finally, the language lists specific ratings, if for some reason the ESRB collapses or changes the ratings (ie dropping AO and changing from T and M to t-13, T-16 and M-18, the law would have to be revised to change the language. If the ESRB is no longer rating games and the new ratings system is not the same, they will have to revise the law. So future proof is out.
It could become more of a headache in the long run.
One final concern I brought up and the report brought up as well, say a movie studio were to make an R rated movie in Oklahoma and a game developer made the game based on that movie in Oklahoma. The game would most likely get an M rating as the source is R rated. Now the movie studio would get the rebate but the game studio making a game on the same source material would not get the rebate. Hardly fair toward the game developer.
All in all, this bill with that provision is very unattractive to any studio wishing to start up or move to Oklahoma. Sure there are a few studios that deal primarily in E-T rated games, but any game developers wishing to make any M rated games whether that is one or a lot, will look elsewhere. Oklahoma would do itself a great favor by dropping the provision completely.
EDIT: One other point, this bill with the ratings requirement forces game developers to seek a rating for all games. Last I checked PC games require no rating unless sold in stores. Flash games require no rating to be distributed. So in effect they are limiting the scope of rebates even further.