I would add that the first person for you to ask this question to is your physician. Depending on the medication(s) you may be taking, the intensity of the migraine, and the type, intensity and duration of the intended exercise probably best answer is for you to see how it makes you feel. Does it cause a recurrence of the migraine? If so, then it’s definitely the wrong exercise. If it makes you feel a bit refreshed, then it’s probably a good choice. Listen to your body to see how it makes you feel.
I agree with Karin with regard to a client who asks you this question, if there’s any hesitation encourage him/her to wait until there’s a comfort level with regard to resuming an exercise regimen.