What I would agree with you is Google's vague statement here:
https://plus.google.com/+NikhylSinghal/posts/MjyncJEbzxKWhat is clear is that GV wanted third party applications (Obihai included) to stop making unauthorized use of their services and it had to end by May 15, 2014. Let's take the "XMPP" out of the equation--as too many people are hung up on that term which I agree isn't in the original Google blog. The result is the same...third party applications that were unauthorized to use GV services were given a cease and desist with a deadline of May 15, 2014.
It was assumed that Google would prevent those applications or hardware from using GV--through unauthorized methods--which posed a risk to the user's security (according to Google). In retrospect, it didn't appear that Google carried out that threat (as of yet) but that was the reasonable impression back then.
Obihai had a reasonable understanding of Google's cease and desist warning. No company whose primary business model was to market a device using primarily GV is going to purposefully destroy themselves economically. While Obihai's wording may have gone beyond what Google had originally intended--
the end result is the same...stop using our (Google's) technology in an unauthorized manner or we will stop it for you on May 15, 2014. Obihai thus had to make their announcement of the impending May 15, 2014 deadline, all the while negotiating with Google in order to be approved. There were no guarantees that Google would approve Obihai or any other third party requesting to use its services so as a business, Obihai could not have unilaterally changed its warning that the services with GV would cease.
Fortunately, Google didn't stop the third party access (probably because of the negotiations behind the scenes) and a settlement was reached in August of 2014 allowing for such usage, albeit in a more secure manner.
When a business like GV sends a cease and desist letter, it was prudent for third parties like Obihai to react and err on the side of caution--hence, their warning of the May 15, 2014 GV with Obi cessation deadline.
The feeling of not getting something for free for perpetuity (after paying $50) seems unfair in an entitlement society but such guarantees were never advertised by Obihai or Google Voice. People will use the service until it is no longer allowed by the discretion of the right holder (here, Google). No one is entitled to anything that a private corporation like Google provides. If one doesn't like it, one votes with one's pocketbook.
