I spent ~25 years in Livermore, and Livermore - SanJo - Livermore over Mines was my favorite and most frequent weekend ride, occasional "long commute" route to/from the Silly Con Valley, and a place to break in new motors.
(such as 2017.. Cal BMW new bike day -> Skyline -> 9 -> hook around the souf bay -> observatory -> Mines -> home.. oil + filter, and there's your break-in done)
The road is not "sketchy" and is in fact one of the best roads I've ever ridden, and I've been around. I miss having it near, and it was about the only thing I miss about California -- friends, food, and Mines. (Scale says says food was #1, whateva...)
But it can be problematic for new riders who combine youthful overconfidence with an immature "riding brain" that hasn't yet had the freeze/panic response worked out of it. So absolutely ride Mines Rd, but adjust the pace so you stay in that "chill flow" zone, no surprises, no stress. Monitor your breathing. If it's anything other than slow and and regular, it means you're pushing things beyond what your brain can comfortably handle, and it's a good sign to dial back until you're in the chill zone again.
It's like with martial arts, sports, music, etc. Takes years to train the brain to perform at a high level and a high speed, in the flow state, handling whatever surprises without skipping a beat. There are no shortcuts to this. So yeah approach your limits to grow, but push them gently. Don't get sucked in over your head trying to match the pace of experienced people. The same corner, the same speed can be a "this is so normal/boring, I am napping with one eye open" to them and a "red alert, I can't make this corner, panic, white knuckle, stiff arm, ride off the road" situation for a newb. That's the difference a few thousand hours of performance riding makes. (A few thousand hours of highway droning doesn't do much.. look at what happens to people who spend their lives riding in Kansas in straight lines and then go to the Dragon).