Yes, I would have come back and asked what "it" was. Why were you telling your T, this person you don't know well yet, about your planning, etc.? If you really want to attempt to kill yourself, no one else can stop you, it's wholly up to you. If you were looking for caring, it's a pretty blunt force, precarious, and personally dangerous way to go about doing so and most other people will eventually resist another's attempt at manipulation of their feelings in that way.

No one hates you or knows you well enough to want you to attempt to kill yourself, die, or be dead. If your T was talking about it being okay to attempt to kill yourself, I think he was only acknowledging that there would be nothing he could do to stop you. What other people do is about the other people. For someone who does not know you well to attempt to try and stop you from attempting to kill yourself, that would be about their worries and feelings, not about expressing care for you at this time.

I would stick around and get to know your T, have some deep, serious, soul searching conversations with him, let him get to know you truly and see if the two of you cannot help you feel better about your life.