By design, contact information is registered along with domains. One function of this is to allow people to report abuse of that domain to a webmaster, and ultimately to pursue action against the registrant if abuse continues. By allowing people to frustrate this resolution process Namecheap are serialising the abuse process through themselves, as they are now the only party with that formerly public information. So yes, I do think it would be appropriate in this case to extend the expense of policing domain abuse to Namecheap and other registrars who provide WHOIS privacy