You are missing the point which is that Akamai can't handle this DDoS.
Do potential customers care if Krebs is a paying customer or not? He went with them as they offer this service which apparently doesn't work as well as advertised.
There is no indication that Akamai can, or can't handle the DDoS. The only information we have is that they are only not willing to do it anymore for this particular customer. There is no indication that they won't do it because they lack the technical capacity to do it. Just as well they might not do it because this thing is financially disadvantageous to them.
As a potential paying customer, what they can and can't do is covered by their SLA, and that's all that matters. If they break their SLA they own the customer compensation. This incident is irrelevant.
Of course I don't actually know what kind of SLA and indemnification Akamai provides. Maybe it's bad. Then after analysing the contracts I would make an informed decision. These things are what I use to make decision, not random stories with no technical or business details on random blogs.
From what I've seen (quoted elsewhere in this thread) there isn't any significant penalty for Akamai if they are unable to mitigate, or choose to not mitigate, a DDoS attack. They might negotiate other terms, but I doubt it. DDoS mitigation is, by its very nature, a best-effort service, and reputation for not giving in to attackers is more important than any contract terms you're reasonably going to be able to get.
Do potential customers care if Krebs is a paying customer or not? He went with them as they offer this service which apparently doesn't work as well as advertised.