I email the portal store with this question an this is the reply I received
"Hi Arlan!
There is no RV Parking past the Lone Pine Campground. I don't know how new this is since your last visit. There are a few options. You can drive up to Horseshoe Meadows and when you get to trailhead call for shuttle service. (If it's after 5 pm or weekend my husband has picked up and drove parties to Horseshoe Meadows.) You can also park your vehicles here at our store in Lone Pine (we have a store in the town of Lone Pine, which I work out of), or also I know of people that have plenty of lots for storage if you opt for removing your camper.
Let me know and the dates you will be arriving.
Janet
Whitney Portal Store Too"
I called Janet after I received the email and she told me she thought the reason was mostly Bear Related. Food in RV's and breakins