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Name linking follows Twitter rules... as in, we use the same matching code as Twitter for their matching, and their usernames do not allow anything other than alphabet, numerics and a very small selection of other characters (which doesn't include &).
It was also how some people avoided being @mentioned because they put non-printing unicode in their username (though unfortunately abuse of that has meant I've now disallowed that).
@Velocio why doesn't my name appear to be hyperlinking?