Well In Intels defence it does make sense to give rebates to your most loyal customers. So with the dell example; when they started using AMD chips this would have meant that dell would have been buying fewer Intel chips.
Lets say that dell originally bought 10 Million Intel Chips and when they started to buy AMD chips they only bought 7 Million chips from Intel. Obviously Intel needs to cut costs and taking away rebates from a disloyal customer seems to make sense to me. For every AMD based PC that Dell builds is technically a lost sale for Intel.
Now they dont give all the details in the article. It might be that Intel told dell and other companies that they would only give rebates/other benefits to them if they did not buy AMD products. If Intel took away the perks for that reason and not because the decline in products bought from their customers... then yes the are