He also did it in a way, that if you chose to take it as cannon, you could, but you didnt have to. I prefer to just think he was gone and never revived. I wasnt one crying for his return. He was probably my favorite character, but I think his passing was a perfect fit with who he was and done properly. I also dont think that "cryo" tube was there to tell the viewers that there is a chance he can come back. I think it was put there to show one last time at Ivanova's refusal to emotionally let go.