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If they put it in their own website's META tag in either keywords or description, then the search engines might take the cue from there and improve the page ranking of the competitor's websites for the relevant keywords that are searched by customers.
I'm not sure if this is copyright infringement cos the intent don't seem to stem from intentional misleading people into thinking that the competitor's website is belonging to Steven's website.
I think it's just a SEO thing. Not really any other things else.
There have been instances of suing over competitor's putting domain names in meta tags. There was a big accounting firm in HK that did this once and had a lot of press.
Anyway I found this. A great reference for all. [murdoch.edu.au...] - Meta Tag Litigation: An Overview And Some Policy Conclusions