What does “We should feel a ‘proxy regret’ for someone / something” mean?

Question

I was drawn to the usage of the word, “proxy” in the following sentence of the article introducing the life and work of Vivian Maier (1926 -2009), a street photographer who took more than 150,000 photographs in her lifetime, while working as a nanny approximately 40 years in Chicago.

Some tellings of Maier’s story suggest that perhaps we should feel a proxy regret, that we should feel sorry about her solitude, her rages, her dark edges, her impecunious existence. Shall we make her a martyr or can we allow that she may have had the life she wanted? How did she see herself? We know that she was looking at that, too—the copious self-portraits prove it. http://www.newyorker.com/online/blogs/culture/2014/05/vivian-maier-and-the-problem-of-difficult-women.html#slide_ss_0=1

CED defines ‘proxy’ as: noun.c.u. Authority given to a person to act for someone else, such as by voting for them in an election, or the person who this authority is given to.

OED also defines it only as a noun meaning;

1. The authority to represent someone else, especially in voting.
2. A person authorized to act on behalf of another.
3. A figure that can be used to represent the value of something in a calculation. None of the above definitions seems to be applicable to the phrase, “feel a proxy regret.”

Is ‘proxy’ in the above quote used as a noun or adjective? What does it mean? Is it like ‘a sort of’?

Answer 1

I disagree with the interpretation provided by Third News. The context of the description of Vivian Maier's activities clearly suggests to me that the adjective which can most readily replace proxy is vicarious -- in other words, meaning 'regret being experienced at second hand', or perhaps 'regret being had on Maier's behalf'.

Answer 2

Proxy regret is a term that expresses 'knowing now what you did not know then'.

Individually:

However innocent our intent, most of us have experienced a proxy regret for childish actions/thoughts, and our maturation gives us the authority to recognize this behavior.

Group:

Societies have experienced proxy regret for actions taken on their behalf (known or not), after the revelation of disastrous or damaging consequences.