Why is it disgusting? As far as I know he was born in England and only qualifies for Ireland through his grandparents, it's only natural he'd have more of a connection to the country he's spent his whole life. We've already given you Jon Walters, what more do you want?
I'm not sure he'll ever be good enough to be an England regular anyway tbh.
He accepted a call-up to an England U15 camp but had to leave with illness when he was 14. If his old coach is to be believed, he only went with Ireland in the first place because the FA hadn't contacted him in 6 months so him and his dad assumed that they weren't interested. He's always maintained that he didn't know who he would eventually play for, so it's not like the FAI didn't know the gamble they were taking.
I'm not sure where Jack will fit in for England. Undoubtedly talented, but is he as good as some of our current wide players? In 2 or 3 years he might be, but I am not sure he is right now. Could be a slow England career