IE was replaced because it was a hole-riddled nonstandard mess, and Google used their position to shove Chrome into everyone's mindshare (something this regulation appears to forbid, incidentally). Chrome isn't nonstandard because Google are very careful to comply with standards - which is easy enough when they have many employees involved with designing them and tend to manipulate those committees in their favor, and even if they fail they can just release whatever they want and use the technology's widespread adoption to justify its eventual standardization. Also, as a modern browser, Chrome is patched frequently, so the security angle is also a nonstarter.