That would actually be good for us. The slower they become, the more nimble us startups look in comparison.

Big companies may be slow, but some of them have significant startup-smooshing power. Presumably, the fear is that the MS-Yahoo conglomerate would attempt to smoosh startups by, say, making everything Yahoo work only with things MS, and generally promoting lock-in and anti-open anti-internet-stuff. It might not work, but when such large objects are in play it seems reasonable to worry.