"The Convention between the United States and China of 1894 provided that
Chinese laborers or Chinese of any other class, either permanently or temporarily residing in the United States, shall have for the protection of their persons and property all rights that are given by the laws of the United States to citizens of the most favored nation, excepting the right to become naturalized citizens."
Wrong. They cited the parents condition in the summary of the decision. Part of that was to ensure that the parents weren't diplomats, but the other part was to ensure that they had 'permanent allegiance' (such as suggested by English common law).
"... of parent of Chinese descent, who, at the time of his birth, are subjects of the Emperor of China, but have a permanent domicil and residence in the United States, and are there carrying on business, and are not employed in any diplomatic or official capacity under the Emperor of China ..."
Also, you're misunderstanding what you cited. The court didn't cite the Convention because they supported how it was applied to permanent or temporary Chinese residents, because the act as a whole was seen as an overreach of power by Congres:
"The fact, therefore, that acts of Congress or treaties have not permitted Chinese persons born out of this country to become citizens by naturalization, cannot exclude Chinese persons born in this country from the operation of the broad and clear words of the Constitution, 'All persons born in the United States, and subject to the jurisdiction thereof, are citizens of the United States.'"
The court acknowledged that permanent allegiance was necesary for the parents in order for the child to be 'subject to the United States' under the 14th amendment.