It's probably not nearly as conniving as you make it out to be. It probably had two intentions, neither of which were as premeditated as you tend to assume:
a) To show another dimension of the race that will generally be overlooked by general viewing public, but which may be interesting to running fans. Everyone in the press wants a different scoop or angle, and given the the attention paid to the race elsewhere, this was one way to grab that scoop.
b) To further underscore how monumental the day was by contextualizing Meb's victory in what some would like to view as a great day for 'America' and 'American' running. Indeed, one might take contention with the fact that others are given a piece of the victory pie, but usually such an attempt at collective pride is not meant to be derogatory, but is predicated on good sentiments. I have a hard to imagining Meb saying, "Hell no, that was allll me, baby!" Such a gracious guy as he is, I expect that he would give credit where credit is due, and even some where it isn't.
It would be a shame if it was remembered as 'Hall's day of virtuousness' instead of Meb's inspiring struggle for victory. However, it seems nice enough that people might remember the day Meb won Boston, and, as an aside, also remember that his fellow runners, with whom he has competed in good sportsmanship for years(!), were equally inspired by his guts and did everything they could to support him.
Probably should have waited a week to let Meb get more attention, though.