I'm not sure if it was the whole of R1, but Grimshaw definitely refused to play it because he thinks that Robbie is no longer relevant. It's no wonder that there are so few artists enjoying long term careers these days when stations like R1 are refusing to play anyone who's been around longer than about two years.
The fact that Candy still got to #1 without their full support just proves how out of touch R1 has become. There are so many songs that become huge top ten hits that Radio 1 never touch, but commercial stations play them ad nauseum. Another example is "Drive By" by Train. Never off Heart etc, I don't think I heard it on R1 once.
Nick Grimshaw doesn't get to choose what's played on his show and he did play Candy (go back and check the song lists if you want). He's also commented several times on the 'made up feud' between him and Robbie and how once again the papers had taken his words out of context (they've done it again today by reporting he blames Harry Styles for being a 'bad influence' on him, when actually it was a Showquizness question and not in any way serious). The made up crap that gets turned into 'fact' about Nick Grimshaw is ridiculous.