from the price match link right above....
"If Staples.com offers a rebate and after the rebate Staples.com's price beats the competition, no price guarantee will be given. You will be getting the lowest final cost by shopping at Staples.com. (For example, if Staples.com's price is $89.99 before a $30.00 rebate then your final cost is $59.99. If the competitor price is $84.99 without a rebate, there will be no price match.) "
So.....IF Staples is offering a $20 rebate on this.....then they won't pricematch down to price....but $20 higher....
Although, the policy doesn't directly say coupons, it wouldn't take much common sense to treat them the same way.....