Age group alone doesn't mean much considering just how far back these demographs go alongside a host of other social issues such as ethnic makeup, prior habitation locations, and someone probably far more important given other matters education.

USA education has become a meme over the last few decades that the kids going through school are coming out stupider than previous classes, so whether or not they even know about the matter at hand here will be a big part of how they respond to the questionnaire.

The fact the term used in the tweet is "Americans" only compounds this because it create a single group that will be raise and lower actual values significantly when more than just age is looked at, but then looking at and reporting on things such as racial PoVs probably isn't in the interests of those looking to continue talking about this.