So Dr. Garner can control lash for Skye, who he's biologically programmed to kill, but not, you know, his wife?
Actually...he never harmed anyone he knew and liked (except in self-defense, and even then he didn't kill anyone who met those criteria). Including both May and Daisy. He was just seemingly incapable of stopping killing Inhumans he didn't already know and like (regardless of whether they deserved it).
Or to rephrase: His degree of control remained consistent and sharply limited throughout.
On the finale: I liked it, felt my predictions were vindicated, and thought it worked well from both a drama and realism standpoint.
And that last bit did indeed raise a variety of very interesting questions that I look forward to finding the answers to.