While Scott could have given an interesting twist to some AIC songs, for him to join the band properly would have been a bad move for two reasons:
1. All his haters would have started calling him a poser again, accusing him of being a cheap imitation of Layne Staley and so fourth... It was a bit difficult to compare Scott to Axl when he joined VR due to the HUGE stylistic discrepancy between them, but this would not have been the case in comparison to Layne... At least insofar as his haters are concerned. And while Scott shouldn't avoid a musically endeavor simply because some people might not like him for it, that brings me to my next point...
2. Scott is just not a right fight for AIC. Although he clearly does have a major rock 'n roll edge, it's just not the same as what AIC was known for. Scott is more is more of a punk-glam-psychedelic-classic-alternative rock 'n roll chimera which--despite covering a whole lot of bases--is not like anything AIC ever sounded like (with the possible exception of glam, but that was in the waaaaay early days). AIC was more of the dirge-metal-grunge-acid breed of rock... And that's just not Scott.
Moral of the story: Scott would not have been a good fit for AIC. MAYBE if he still sang and acted like he did in the Core days this idea would work, but... That's neither here nor there.