In economics and finance, arbitrage is the practice of taking advantage of a price difference between two or more markets: striking a combination of matching deals that capitalize upon the imbalance, the profit being the difference between the market prices. When used by academics, an arbitrage is a transaction that involves no negative cash flow at any probabilistic or temporal state and a positive cash flow in at least one state; in simple terms, it is the possibility of a risk-free profit at zero cost.
On the Reddit Bitinstant thread http://www.reddit.com/r/Bitcoin/comments/1bzo49/do_not_use_bitinstant/ Bitinstant claims they pay you in coin at the value of the Mt. Gox Avg. at the time of deposit.
However, you could be correct, it could be a desperate attempt by Bitinstant to recover the $12,000USD they got hacked for.
In that case they "ARE" doing with our money what we are "TRYING" to do with our money.
It would be a profitable gain, but a huge Pulic Relations loss.