I would keep mine in if she had it, but not on the off chance that she would develop it! When there was chicken pox going around baby bailey's nursery, she'd been hospitalised by a stomach bug so I kept her off nursery a little longer than needed, so that she didn't get CP too, but normally I wouldn't have minded, like everyone has said she's going to get it at some point.
Having said that though I did keep her away from her cousin a couple of months back, who probably wasn't infectious any more, on the off chance that if she caught it from him she would be have it on her 1st birthday!! :(
Maybe they're just making excuses not to see familly members - I might start doing that lol!!