Likely more problematic is that he is personally invested in his wife. One of the primary reasons candidates hire experts to guide their campaign — aside from their experience and expertise — is that they are dispassionate. Candidates may react to an attack emotionally, but a campaign expert may advise that it is wiser, for example, to ignore an attack. Spouses, one assumes, may be even more emotional regarding an attack on their loved one than the candidate, herself (on the other hand, family members, like Bobby Kennedy, sometimes can be both competent and trustworthy campaign aides).
Lastly, is there a chance that Todd’s involvement might make Sarah Palin look like the weak wife who needs protecting?