Castration has no magical calming effects on rodents whatsoever. They will still behave like they are entire, they just won't be able to reproduce after about 6 weeks. Not all chinchillas WANT to be cuddled and sometimes we have to content oursleves with just watching them play, coming to us to grab a treat from us if we are lucky. Out of the 7 chins I own, only one will come and get onto your arm and actively seek out fuss and attention. 5 others will accept handling but do not want to be 'cuddled' for long and one absolutely detests handling though I can get him if I need to. He was very aggressive when I got him due to having been teased by someone but he accepts me being around now and will take treats from me.

Chinchillas are not often 'cuddly' and we as their owners have to respect them and allow them to be them. Why not have him castrated anywayand then after six weeks see about getting a female to introduce to him? There are chinchilla forums out there who will gladly guide you through the introduction process.