The only reason I can imagine is - well, two reasons - either they did not have a tow line or they were ordered to stay in place until whatever was wrong was righted.
Either way it looks really bad for the Navy’s preparedness and command level decision making (unless orders came from the US ...)
They did not have an anchor??? It is possible to use something not designated as a “Tow” rope to tow a vessel. I cannot believe there was not a rope onboard that could not have been used as a “Tow” line.