I don't buy at newegg or have any other incentive to side with them but... in my past experiences, Linux didn't really have the most compatible hardware drivers. Am I the only one to think that?
this is a thinkpad. they've always been the top-end linux hardware of choice. i've had thinkpads for decades with linux. as long as you select the right wireless card there are no issues - distros even have special packages for thinkpad compatability.
It's not relevant; the owner tested it with a Windows install on a USB stick to ensure Linux wasn't the issue. And while Linux doesn't always have the most compatible drivers, I've never seen them fail in that kind of way.
Anyway, the problem here is that Newegg are refusing to replace it simply because of the presence of Linux; by far the most likely explanation is that the hardware really is defective and Linux isn't at fault.
Is there anything in the returns policy to prevent you installing your own custom drivers under Windows? From the quoted bit, it didn't look like it... If that's okay, why shouldn't installing Linux be okay?