Now because, as I said, there will be more people who are heterosexual than homosexual, more children will see the heterosexual kiss and think "Oh wow, that looks like a fun thing to do, maybe I should try it on that member of the opposite gender I like" than any who would see the homosexual kiss and think the same thing (except with 'member of the same gender' instead of 'member of the opposite gender'). This is also assuming that the young child already knows thier sexuality, in actuality children probably will not know their sexual preference before around the age of fifteen, and most younger children (who would later turn out to be gay) will just think that they like females because heterosexuals are more abundant and will be seen most often by the child. So logically this plan fails.
This plan also fails morally, there's quite a double standard in claiming that homosexual kissing is sexually suggestive but that heterosexual kissing is not. If it happened, it would be a clear step-back. Assuming there is anything wrong with gay kissing but not with hetero kissing is a very bad assumption. Then maybe ten years along the lines people will think "Hmm, gay kissing, that's not allowed on television until late, why's it allowed in public at all hours?" and slowly snowball down that hill of immorality.
I realise it is unlikely that this crazy law will come to anything, but I think it needs to be pointed out just how stupid the idea is.