It is a very normal provision. In fact, it's in every version of an implementing statute for a treaty that we have on the books. It essentially is a reflection of the fact that a treaty, in this situation, is protected by the Constitution.
Occasionally, there are situations where there can be interpretation challenges, like the situation of inconsistency or conflict that it describes. Including a provision like this to account for that unlikely but still possible inconsistency or conflict is very standard and helpful in terms of ensuring that the treaties and the act can be interpreted properly.