There are lots of good things about Cruz, but on this point he is totally mistaken.
I am sure that there are sleazy, nasty, despicable defense attorneys, just as I'm equally sure that there are sleazy, nasty, despicable prosecutors, but - IMHO - the only lawyers who, as a group, still really deserve the honorific "profession" are defense attorneys.
Whatever their motivations, lawyers who become prosecutors always bear at least some of the personality defect that, if given in to, causes them to become fascists. On the other hand, the defense lawyer is often the only person standing between you and a lifetime of hurt at the hands of a vindictive or misguided government. And it can be a very lonely, stressful, monetarily unrewarding stand as well - as Cruz' comments make clear.
So, Cruz should STFU and apologize to the defense bar for his comments.