Bitter, much, Simon? Niall Horan is being slammed by the man who helped jumpstart his career, saying that Niall’s debut single would have peaked higher on the charts if he had stuck with the ‘X Factor’ creator’s label instead of signing with Capitol Records. Get the scoop on Niall’s alleged lack of ‘loyalty,’right here!Simon Cowell, 56, took a major dig at his former protegeNiall Horan, 23, after the surprise release of the young artist’s new single, “This Town.” Even though the single haspeaked at number nine on the charts, making it Niall’s first solo top ten single, Simon said that if Niall had decided to work with his label, Syco, instead of moving to Capitol Records, it would have been a smash hit. “He probably would have had a number one single if he’d stayed with me. But you know who does have number this week?James Arthur. Very pleased he’s back with uswith a fantastic record. Hashtag loyalty,” he told the Sunday Mirror.Ouch!Niallsurprised his fanswith the release of the track via his Twitter account on Sept. 29, a few months after One Direction’s hiatus began. “Been workin in the studio, wanted to share this song I just wrote with u guys. thankyou for always being there,” he tweeted. This announcement came on the same day he also revealed he had signed with a new label.“I’m excited to announce I have signed a record deal with Capitol Records USA and released my first solo song. Thank you to all the One Direction fans for your love and support as always. I’m looking forward to the next part of this journey together,” he said in astatement.Niall Horan & Celine Helene Vandycke — PICSClearly, this move hasn’t gone over well with Simon, who probably wanted to keep Niall under his wing. But we wish the best for the Irishman in his new solo career, and with his new label. Honestly, we love “This Town,” andwe really hope to hear some more amazing music from Niall in the near future!