Note that the road is not expected to open until mid 2019.
Having visited the site today, it does not appear to be an option to take access along the road on foot or mountain bike. Rather than waste a day, it would be better to take one of the alternative options:
For Spidean Mialach, take the right-of-way from the roadside just short of Kingie and approach the Munro along its Eastern ridge. Return the same. If for any reason you need to descend to the road alongside Loch Quoich, this should be treated as an emergency which should be notified to the Police as there is no safe way past the Quoich Dam and the alternative route (an ATV track) provided for estate use involves a river crossing which could be hazardous.
Other Quoich mountains would require access from Glen Kingie, Loch Arkaig, Arnisdale and/or Barrisdale or even Glen Shiel. All involve longer approach routes.
I was thinking the same, but apparently only one resident is affected on a daily basis. He works for one of the estates and has a daily travel across the dam, the ATV track and across the river to keep an eye on some farm animals and back home. I think he lives up in Glen Quoich. He's going to have a quiet Christmas!