Lawsuits in US courts are not "interference of the United States," unless the United States is the plaintiff. In the US, courts are limited to hearing disputes between private parties. The US courts do not (as in some jurisdictions) have any proactive, prosecutorial or investigative powers. (In limited circumstances, in the context of an actual litigation, the court can appoint experts, but that's about as far as that goes.)
The cases Rubens cites are disputes between private parties or between a private party and ICANN. The US court is the forum for those disputes. This is not "interference of the United States."
If ICANN were located in another jurisdiction, that jurisdiction's courts would be hearing these disputes. Notably, ICANN is subject to being sued in other countries where it has offices, so there are already alternatives if plaintiffs want to find a different venue in which to seek redress. While this is a possibility, I believe all plaintiffs that have sued ICANN have done so in the US. This may say something about the appeal of the US as a jurisdiction for resolving disputes.
Greg