Irrespective of whether it's right or wrong to stand up at matches, why should the fact that there is a healthy 70 year old woman standing up at matches mean that every other person going is therefore healthy enough/able bodied enough/tall enough to see stood up?
Again, as standing areas are illegal, we are never going to have a designated standing area. Choosing to stand wherever you feel like it will almost certainly create problems for others who don't have the option of standing.
Personally, I think standing areas should be brought back. There's no reason not to have them. However, for as long as we don't have them, standing up will always cause problems for people who prefer to/have to sit.