Hodgson claimed he had overlooked Ferdinand because it would have been wrong to have him in his European Championship squad and not in the starting XI.
The new England manager told ITV: "Rio Ferdinand for me is not a player that you call up as a substitute, or to cover for the players that you have.
"We turned to Martin Kelly because I knew he was going to be someone who would be very useful to us. He's very happy to be here knowing that his chances of playing a big part in the tournament are quite small. You don't turn to people like Rio Ferdinand for that."
The backlash against Ferdinand's omission has threatened to overshadow England's EURO 2012 campaign, which they begin on Monday. Hodgson insisted when naming his original squad that the 33-year-old was left out for "football reasons".
But his refusal to go into detail about those reasons fuelled speculation which intensified when calling up rookie defender Martin Kelly for the injured Gary Cahill. Ferdinand himself tweeted, "What reasons?????!!!", while his friend and agent Jamie Moralee branded the decision "disrespectful".
The Manchester United star believes his international future may be over but Hodgson told BBC Sport today: "Ferdinand has no reason to fear for his international future. All the time he's playing, I'll keep watching."
Hodgson said there was never any prospect of Ferdinand being selected for EURO 2012 when Cahill was injured, claiming he had even considered recalling broken-toe victim Kyle Walker.
"Our first thought was Kyle Walker because he was one of my original selections," he said. "We did get in touch with him just to check whether the toe had cleared up. It hadn't, so then we turned back to Martin Kelly. There was never any question of, 'Which player should I take here?'"