It would have been "big" news if Sony bought a lot more shares or if GNUS wasn't in the act of selling shares. As you say, Sony's level of commitment isn't very high. I think more than 10% would have made for "big" news.
I do like a large company owning shares, and not enough to block a buyout by another company.
It's probably worthwhile to look into Sony's public plans for content creation acquisitions. Disney' buys of Pixar, Marvel, and Lucas Films has worked out well.
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