claiming that Sam's kid is his biological child. He knew that Heather was up to no good from the get-go because she had AZ's dead body when he met her at the shack so the excuse that Sam didn't want the baby never held water since he believed that she had killed AZ at that time. Also, because of that, he knew he couldn't trust her at that time.
And considering that Carly is supposed to be Jason's best friend, the fact that Todd actively stole his kid is a bigger deal - not in how it relates to Sam or Jason but to Carly.
Todd, however, got rid of Jack when he was born and let Blair grieve for her dead kid so some of Todd's actions aren't out of character. Todd letting Heather live and be a threat to him IMO is out of character.
