Is it ok to be editing a post that might render someone's comment on that post as irrelevant?
Yes, this is perfectly okay. Not only are comments largely irrelevant, but they're also ephemeral. One of their main purposes is to make a temporary suggestion to someone on how to revise or clarify a post. Once that's done, the comment serves no purpose and should be removed.
What is the nice way to let the author of the comment a chance to edit remove it?
1. leave a comment mentioning the original comenter explaining I rendered his comment obsolete?
I would definitely do this. Use the
@reply system to send a courtesy ping to the user who left the original comment, informing them that you've made the suggested edit. This serves several purposes:
- If they cared enough to leave a comment, they probably care about the topic under discussion. This gives them a chance to read your new thoughts, and if necessary, make further suggestions.
- It gives them a chance to remove their now-obsolete comment.
- If they downvoted, it gives them a chance to remove their now-invalid downvote.
If they never do come back, or never remove their comment, you can always flag the comment as "obsolete" to have a moderator remove it. Be sure to remove your response, also!
2. do nothing, such is the way of life
That might be the way of life, but I'm not sure it's particularly advantageous here.
3. not edit posts that will make someone's comments look, well, silly
No, this would definitely be the wrong thing to do.
4. mark it as a great comment to ease your conscience
I guess you could, but this does seem rather pointless.