About a year ago, the park vendor that runs the lodges there was complaining that the park service wouldn't let them put one in; they had had several requests. I'm glad they finally managed to get it done. Note, however, that there are several campgrounds just outside the park that have cabins and 14-50 outlets. That's what we used--you can cover the park pretty well if you start with a full charge from the outside.
If the federal government is serious about promoting EV adoption, installing EVSEs in all the national parks and monuments (outside of urban areas) would be a simple place to start. Driving electric in pristine wilderness should be strongly encouraged!
I talked to a ranger there couple of years ago. According to him, one of the issues of putting chargers there was that they were not getting enough power into the valley.
Yep, I could see how that's a problem. Of course, we know that the RV parks have plenty of power available, so it's really just the distribution lines into the park (i.e., the park's problem), not the utility distribution system.