I don't think the US is concerned with this at all. This piece is just propaganda to make Bitcoin look like a villain and Ripple a hero. Anyone who knows how Bitcoin works know that majority being behind the great firewall doesn't mean that China controls it. It's a nuisance because China could cause miners a serious headache, but it's very fixable, and miners are making it even more fixable by distributing their farms elsewhere.

Overall, there is some cause of concern, but any problems that may arise from it are short-term and doesn't threaten Bitcoin's well-being at all.