He was the national coach when McIlroy was first selected to play for Ireland and he also is excited at the prospect of playing with some of his former teammates.
McIlroy, who won the PGA Championship in 2012 and '14, said that made him start questioning who he was and where his loyalties lie.
"It is just one of those things where it is in the middle of a really busy stretch but right now in my mind I will most likely play".
The men's Olympic golf will be held at the Kasumigaseki course in suburban Tokyo from July 30-Aug. 2.
Returning to the subject later in the press conference, McIlroy continued: "I think as a young boy it was always my dream to play for Ireland".
"I wanted to play for Ireland, I was very proud to put on that shirt or that blazer". It's seen as a whole island sport, just like hockey is, just like most of the sports are. It's something that you have to really believe in.
'I said to Justin, if I had been on that podium listening to the Irish flag or the British flag, I would have felt uncomfortable either way, ' said McIlroy at the time.
"So why would it be any different just because it's a different golf tournament or because it's a different arena or a different environment?" he added.
"I've thought about that for a long time, and in the end, it was the fact that when I was a little boy and I got that first call up to the national squad to go on to Citywest and be a part of the youth system or the boys or whatever, you know, and making that team and playing in home internationals, I was so proud to do that". McIlroy had been scheduled to play for Ireland in 2016 until announcing that June he would not be going.
'So, it's going to be a great experience and probably a bit nostalgic because it will take me back. It's going to be cool'.
'I don't know the words to either anthem, I don't feel a connection to either flag.
"It put me in a position where I had to question who I am, where am I from", he said in 2017.
The Northern Ireland golfer acknowledged at the time that he would inevitably upset some people no matter who he chose to play for.
McIlroy, who represented Ireland throughout his amateur career, said his decision to pencil Tokyo 2020 into his schedule was helped by the as yet "unofficial" appointment of the Golfing Union of Ireland's national coach Neil Manchip as Olympic team leader and the chance to rekindle the good memories of his amateur career.