In general, yes — China is a very safe country to travel in, and that includes walking around after dark. Two qualifications, though. On the plateau the real risks are the road, the altitude and the animals rather than other people. And nowhere is risk-free, so looking after yourself still matters — that part is yours, not mine.
Day to day
Walking at night is normal here. Crime against visitors is rare, and I have never built an itinerary around avoiding a particular district. The towns on these routes are small and quiet; the biggest city you will see is Chengdu, and it feels considerably calmer than a European capital of the same size.
What actually goes wrong
On these roads, honestly: driving days that are too long, altitude, and animals. Dogs around villages and monasteries are a more real hazard than any person you will meet. Winter adds ice to the passes; summer adds the possibility of a landslide closing a road for a few hours. None of that is dramatic when the days are planned with a margin in them, which is why I plan them that way.
The part I cannot take off your hands
I check the roads, plan the days, watch the weather and carry what a car should carry. What I cannot do is be careful on your behalf. Watch your footing at 4,000 m. Keep an eye on how you feel and say something early. Don't walk off alone across open grassland in the dark, and don't treat a monastery dog as a pet. Your phone and passport are worth keeping where you would keep them in any city.
None of that is meant to frighten you. It is the same ordinary care you would take anywhere — and it is the half of safety that makes the other half possible.
Questions I get on this one
Can I walk around at night?
What about wild animals?
Is there anything about the region itself that is dangerous?
Should I be worried about anything specific as a visitor?
From what I see on the road, not from official statistics. Related: altitude · insurance · all essentials