(We have been depressive the last few days, but this is not in response to anything anyone close to us has done and it is not meant to indicate that we are currently feeling suicidal.)
It is always a bad idea to tell someone how unacceptable the choice to kill theirself is. Or to tell others, post-mortem, how unacceptable a suicide victim's choice was.
Because it's not really a choice. It can be a cry for help, it can be a last-ditch escape, but it's never a rational choice in the same way that, say, participating in Nanowrimo is. It's a self-centred choice, but you're never quite so self-centred as when you've become convinced that you shouldn't or don't deserve to exist.
You don't wake up and decide "I want to be really mean to my friends and loved ones today," not any more than a feral fox decides "I'm going to murder a rabbit today." What's necessary for you has suddenly become incompatible with what is convenient, or even necessary, for others. So it doesn't matter how socially, personally, professionally, or even legally unacceptable talking about wanting to kill yourself is, and all that forbidding it does is turn "person at risk of suicide" into an out-caste.
Which, in turn, makes suicides more likely, because it places a lot more pressure on these people and makes them less likely to talk about it.
If you personally can't deal with a suicidal person, because of triggers or prejudice or just plain not knowing how to help, it is not your fault for not helping them, because you can't to begin with. You can try to learn to relate, and to educate yourself about the reasons why people feel this way (mostly economic, political, or medical) and what you can do about them. But heroes are called that because they're exceptional, and no one should blame themselves for not being one.
Going on living when you're suicidal is also a heroic act, though. Asking that of someone you care about is understandable, but demanding it of them is wrong. And mocking or threatening them -- like the person at The Major News Site who basically said she would call the police if I didn't tell her I wasn't going to kill myself after a despairing post I made on their forum the day that I lost my job, or a jerk I read about who got banned from FA for trolling a dead furry's suicide note -- is not only wrong wrong wrong, it also makes things worse for everyone going through this.
It places the burden for dealing with suicidal people onto said people themselves. Which doesn't help anyone, least of all the ones who will have to deal with their loss. And if you are one of those people, those supposed friends and loved ones, it sends the message that their being at risk of dying is a problem for you and you expect them to fix it.
Which is more self-centred than wanting to kill yourself in the first place.