Likely due to the fact he went through the Irish youth set up at pretty much all levels, made 3 appearances for the senior side then jumped ship.
Yes all this. It's not that he could've played for us and didn't, it's that he actually did fucking play for us and then went turncoat.
And he didn't just go as far having three senior caps - he also indulged in all this badge kissing and the nonsense "up the 'RA" tweets, as though playing for Ireland was what he really wanted. Then goes and jumps ship at the first sign of England interest. Suggests he's a two-faced dickhead. If Madrid came in for him in a year's time, he'd probably act the prick to force a move. Comes across as extremely false to me.
It shouldn't be confused with Jack Grealish, who also played for ireland at all the underage levels, but never the senior team, and never did all the performative badge-kissing shite like Rice. When he went to play for England it was very disappointing, but somewhat fair enough. Now Grealish is a dickhead in plenty of other ways, but I don't hold the Ireland thing against him.