This argument might seem legit, but it really doesn't hold water.
Think about it, if NE had any intention of drafting Harris they could have taken him at 28th overall, after having already selected Meriweather. So, it wasn't simply a choice of Harris or Meriweather. Also, I doubt Harris would have got so much playing time his first year if NE had drafted him, as they have Seau, AD, and Bruschi. Maybe his playing time would have increased with Colvin going down, but I'm willing to bet he'd still be a backup (like Meriweather) right now.
We should also give it a few years before deciding which is the better pro.
Incidently, I've argued with Chris Landry before. He told me Lendale White was a better pick and made more sense for NE than Maroney. I disagreed, and said I thought they would pick the Golden Gopher RB. If he's saying David Harris is the Defensive Rookie of the year, I'll again disagree with him. Patrick Willis has proven to be every bit of the LB some of us believed he could be, and he'll likely win the award.