JWs pay out Christians for wearing a cross as being idolatry. They reason that the person must be idolising the symbol, rather than using it as a reminder of Jesus. How is it different that the jw.org logo is not considered the same. In fact it should be considered to be worse, as it is idolising an organisation instead of Jesus.
The jw.org logo is a reminder of the organisation, just as the cross is a reminder of Jesus, and not an idol at all. But it does highlight the double standard JWs have for themselves when compared to others.