The MLS champions initially said they would not clear captain Keane for Republic of Ireland's June friendlies with England and Georgia but have since retracted that stance with Arena suggesting it would be hypocritical to disallow the striker to play for his beloved nation.
"In reflecting over it, I think if we're requested to release US players, then how can we not allow other internationals to go," said Arena.
"We're allowing US players to play in friendlies, then we have to do [this]. It creates an awkward situation, but it's fair.
"In reality, no player should be released (for friendlies). US player or other internationals. We should adhere to FIFA rules.
"If our US internationals are going for friendlies, then others should. We're on the same page here. It's not one rule for one and one for another."