I haven't seen a sitemap.php in a long time, Sha. Certainly Google could read it if they want, but whether they will or not is the question. I would be inclined to doubt it.
If he says that it's generating a sitemap.xml, but none is present on WMT, then I would respond that one of two things is happening:
1. It isn't generating the sitemap in an xml format at all, but only in php, or
2. For some reason, the xml version is either not transmitted, or not received.
The only other possibility that comes to mind is that perhaps the conversion from php to xml is not tagged in a fashion to be recognized as an xml file, and WMT is detecting it as php and assigning it that status accordingly. I suppose that could happen, particularly if he is using an outdated plugin or if of his own coding, the conversion is faulty.
I'd be interested in hearing what you ultimately learn on this.