The "Quad" can only promote exclusion, as it's based on an old-fashioned US mentality of hegemony as well as ideological and military conflict. As a better alternative, all nations in the region should work together to support collective security, stability, and prosperity.
This trip will send a strong message to Pyongyang and Beijing by showing that Biden seeks to strengthen the US' relationship with its allies. The US is committed to a free and open Indo-Pacific, and these alliances are vital to ensuring a rules-based global order.
It's unclear whether the Quad will actually amount to much in the end. It has a ways to go as a functional group, and all four countries believe economic relations can be separated from geopolitics - a thought Beijing concurs with too. Without a strategic vision or even an agenda, the Quad has a lot of work to do before it can even begin to make an impact.