You do not know the facts of Rinoa's future, so before you start spouting off about whose argument is unsupported, perhaps you should consider your own position. I am speculating here, and my speculation is logically justified. If you want to have a full blown argument about the effects of time manipulation, then by all means generate a thread.
If Rinoa ever did obtain the power for time manipulation, she might become corrupted and turn into Ultimecia (Ulcia) in the future, and seek to compress her present time with her past time when she was Rinoa. Since she controls time, killing herself in the past may not have any effect on Ultimecia (if she is Rinoa) because she has stepped outside of the linear time effect. Actually, she would probably want to kill her past self as to safe guard any kind of threat to her current state and power. This explains why Ultimecia nearly caused the death of Rinoa on disk three.
Also, Square has merely stated that sorceresses have normal life spans, and you have assumed through sophistic logic that this proves Ultimecia as an entirely different person from Rinoa.
Lastly, all my arguments are solidly grounded in fact and logic, and if you want to take up anything else I've said on these forums, then by all means do so. I’m always ready to admit to being incorrect or to refine my position if it is met with a greater argument. I'm not stating for sure that Ultimecia is Rinoa- I am merely remarking on the logical possibility of such a thing. Subjects such as time manipulation require an open mind to comprehend new plausibility.

imp:
-LYCHON