I mean it's a shame for their fans, but you can't fault them for take a big opportunity like that. And if they're a fan of Chunk, they probably love ADTR too so they won't mind shelling out the extra dough.
Yeah you're definitely right, smart career move by Chunk for sure and I can't imagine a Chunk fan who doesn't like ADTR. I just can't shake the feeling that I'd be annoyed if a band I liked did this.
Either way, this really does work out for all the parties involved, save for maybe a few annoyed fans.