TD,
The prohibition of work on the Sabbath was never recognized as being monolithic in application. Sabbath law may be rendered either dechuya (suspended) or hutra (abrogated) by the circumstances pertaining to the work. One of the classic examples from Rabbic literature is the collapse of an occupied building on the Sabbath. The backbreaking task of clearing the rubble in search of survivors is "work" by any definition of the word. Yet it is not "prohibited" work. Jesus did not arbitrarily break the Sabbath simply because he (allegedly) could. In both of the instances you cite, Jesus not only gave reasons that were perfectly viable within halacha, he cited precedent as well.
You are correct as to rabbinical interpretation. However, where do we get the idea that Jesus had any conflict with the "Pharisees" regarding the sabbath in the first place? From the Gospels, which happen to misrepresent the Pharisaic stance as an overly strict one and then ascribe the actual moderate Pharisaic stance to "Jesus," making him appear more humane etc. Moreover, "Jesus"' argument repeatedly implies that he is above the law (as "lord of the sabbath," Mark 2:28//, or "greater than the temple," Matthew 12:6). John clearly states that to "the Jews" Jesus is "breaking the sabbath" (5:18). Similarly, on the issue of ritually unclean food, "Jesus"' argument does not imply that "this food is not unclean" but that "there is no unclean food" (Mark 7//, note v. 19).
Bottom line: this is a purely fictional conflict, reflecting the anti-legalistic, and, more generally, anti-Jewish stance of hellenistic Christian circles with some knowledge of late 1st-century Pharisaic halakha. As a historical account it would make no sense, since as you pointed out the Pharisees did not hold the view which the Gospel ascribe to them (not to mention that the Pharisees were certainly not that influential before 70 AD). It is a strawman argument.