Yes, some older women can wear long grey hair beautifully. It depends on the hair texture and how thick it is. I have fine hair and have lost a worrying amount because of illness and genetics.
I’m in my 6Os now, and my hair used to be halfway to my waist until a few years ago. I thought I was going to be an old lady rocking long grey hair. Alas. It became very stringy looking. It’s sitting on my shoulders currently, which looked okay for couple of years (bit Jackie Kennedy in the 70s only grey, not dyed) but it’s grown stringy looking again - the length is dragging down my face and I can’t be arsed putting in all the work in to only have it look okay for a couple of hours at most. I couldn’t have hair extensions because it’s thin on top - even if I could afford the good ones and could be bothered giving up hours of my ever decreasing time.
Hair doesn’t only just change colour as we age. I will be having it cut into a just below chin length bob the next time I get to the hairdressers - it’ll be my ‘Helen Mirren years’. I figure eventually I’ll be wearing a ‘Judi Dench look’ or a grey version of ‘Isabella Rossellini hair (love that woman - she’s a glass half full person. I follow her on Instagram. She is interesting).
More power to older women that can wear long grey hair - some can. It used to be a shibboleth almost that old women’s hair had to be short, but it is no longer. Sometimes it’s just the reality.