I do think the apology was a little weak but he basically did do what was necessary, in other words he said they were wrong and did not have a policy of against selling to gun related businesses.
I would have preferred a much stronger apology but he has to walk a tightrope of sorts on these politically charged issues.
It was weak, but it was adequate. From Michael Dell's point of view this whole thing is being blown way out of proportion: They had a breakdown in communications with a customer, and suddenly they find themselves landed on by pro-gun people all over the country.
Well, it's a good object lesson for Dell and for other companies: Don't mess around when it comes to 2nd Amendment issues. This one incident is going to continue to echo around the Internet, and Dell sales reps will be fielding angry questions for weeks and months to come. It will probably end up costing Dell millions of dollars in lost sales. They'll be walking on eggshells in the future for fear of offending more customers.
So I think Dell has been adequately punished for its error. Let's (justifiably) declare victory and move on.