Vested interest
He would say that wouldn't he, being at the helm at that time and I'd guess he still has some shares...
"with retailers followed a strict manual which limited the rebates they could offer and other aspects of trading"
That's fine, but what happens first is the retailer is offered a much better price if they restrict / limit their sales of AMD hardware. I would think the same is happening at Dell; though Intel will be careful not to make things totally obvious - i.e. encourage a sales of lower value products at low volumes.
If they have 70% or more of the market I would think they should be considered to be in a monopoly position and regulated as such.