The Heritage Foundation are a far right US organisation usually more focussed on abortion and birth control bans, stoking culture wars, and supporting far right figures. So why should they care about Prince Harry's visa?
I should add I do not care about Prince Harry, he is a rich man who will be fine.
But the Heritage Foundations involvement seems to stem from a desire to use Harry as a test case to get access to what are usually private documents. As I see it, if the Heritage Foundation can get public access to Harrys visa documents, it sets a precedent that allows them through the courts to access anyone's visas documents. This can be used to try and deport anyone political who threatens the political vision of the Heritage Foundation.
There are plenty of civil rights lawyers, political activists, and prominent human rights activists who may at some time have smoked weed in college or other minor infractions. Getting access to these individuals visa applications may provide an opening to deport these individuals.
Disagree or have another theory? Because I do not think it is a coincidence that an organisation as politically astute as the Heritage Foundation is trying to get access to Harrys visa. This is what they do, find a wedge issue to help them meet their political aims.