The true question here is, How much did that ICO paid Binance to do it, Ir if there are not maybe Binance really seen a potential with their project, And because it is Binance many people will sure trust it, The brand name is really important and just like in TV programs if the channel is very popular many audiences would surely trust it, And Binance is one of the tops and trusted Exchange in the community, So there is no doubt about it.
Of course it would be expensive to list an ICO in binance thats for sure, but this exchange is one of the few that are trusted, established, and had successful ICO's. So, I guess Binance wont just allowed an ICO that doesnt have a good dev and team behind it, or else it would ruin their reputation.