The case of Channa gives us a number of reasons to question the views on suicide in the Pali Canon.
First, there is no reason to think that the exoneration of Channa establishes a normative position on suicide. This is because to exonerate from blame is not the same as to condone.
Second, there are textual reasons for thinking that the Buddha’s apparent exoneration may not be an exoneration after all. The textual issues are complex and it would not be safe to draw any firm conclusions. It might be observed in passing that the textual evidence that suicide may be permissible in Christianity is much greater than in Buddhism. By comparison, Theravāda sources are a model of consistency in their refusal to countenance the intentional destruction of life.
Third, the commentarial tradition finds the idea that an Arhat would take his own life in the way Channa did completely unacceptable.
Fourth, there is a logical point which, although somewhat obvious, seems to have been overlooked in previous discussions. If we assume, along with the commentary and secondary literature, that Channa was not an Arhat prior to his suicide attempt, then to extrapolate a rule from this case such that suicide is permissible for Arhats is fallacious. The reason for this is that Channa’s suicide was—in all significant respects—the suicide of an unenlightened person. The motivation, deliberation and intention which preceded his suicide—everything down to the act of picking up the razor—all this was done by an unenlightened person. Channa’s suicide thus cannot be taken as setting a precedent for Arhats for the simple reason that he was not one himself until after he had performed the suicidal act.
Fifth and finally, suicide is repeatedly condemned in canonical and non-canonical sources and goes directly “against the stream” of Buddhist moral teachings. A number of reasons why suicide is wrong are found in the sources but no single underlying objection to suicide is articulated.
Reference: Damien Keown (1996), Buddhism and Suicide, the Case of Channa, pp. 8–31.