After weeks of emails to HTC, I have received their boilerplate "within 90-120 days" response along with an invitation for further comment. Now on to the next step...
I am very sorry to hear this, as I expected a different answer. Is HTC aware that it is violating GPLv2 with this policy, and leaving itself open to enforcement action by the Free Software Foundation?
Please refer to Section 4.1.2 of the compliance guide, which states that source must be made available at the time that a device is shipped with an offer of source. Below, I have provided a URL as well as cited the relevant portion for review.
It would be regrettable for me to have to refer this matter to the FSF for enforcement action. Hopefully further review will clarify where HTC is incorrect in its source distribution policy, and corrections can be made to avoid non-compliance issues.
Finally, it is unacceptable to use option (b) merely because you do not have Corresponding Source ready. We find that some companies chose this option because writing an offer is easy, but producing a source distribution as an afterthought to a hasty development process is difficult. The offer for source does not exist as a stop-gap solution for companies rushing to market with an out-of-compliance product. If you ship an offer for source with your product but cannot actually deliver immediately on that offer when your customers receive it, you should expect an enforcement action.