I think that there must be some truth to this.
Everything you summarized points to Curran being wrong.
1. Patriots made an offer.
2. Welker thought it was very low. (If fans had known about the offer, there also would've been 'this is too low', 'its an insult' outrage on these boards; myself included).
3. Welker went out to get better offers.
4. Welker realized the original offer was at his market level, and found another one slightly more (the fact that his best offer was at 6m is a shock to me).
5. Welker wanted to remain a Patriot -- so asked the Pats to match
6. Pats decided the offer was their max offer
7. Welker signed elsewhere.
There doesn't seem to be any ego or spite in this sequence on Welker's part -- if you're spiteful you pull a Ray Allen and sign for less; not ask for your team to match. And surprisingly, on the Pat's part, they judged the market completely accurately -- offering him 1m/year less than the best that the other 30 teams could do.
The only thing that was maybe mis-judged by fan is that Welker would decide to take a home-town, 20% discount.