I don't agree, I think Microsoft would gain MASSIVE benefits from a Square-Enix acquisition. It would provide them with the opportunity to gain even more traction in the west Asian market, most importantly Japan. Having Final Fantasy and Dragon Quest focused on Windows/Xbox would be a huge blow to Sony and even Nintendo.
Its more likely that it would kill those IPs than boost Xbox to Sony's level. Which is why JP dev studios are not siding with MS, because most of their fans are on Playstation.