Edit: OK, I've turned on "Show dead" and there it is. My guess is that it was DOA. Lots of submissions are DOA, and the reasons vary. You're best to follow the advice in the Guidelines[0] and email the mods.
And it also appears that your question is answered in the FAQ[1]:
"Why can't I post a comment to a thread?
"Threads are closed to new comments after two weeks, or if the submission has been killed by software, moderators, or user flags."
3 comments
[ 4.9 ms ] story [ 29.5 ms ] threadEdit: OK, I've turned on "Show dead" and there it is. My guess is that it was DOA. Lots of submissions are DOA, and the reasons vary. You're best to follow the advice in the Guidelines[0] and email the mods.
And it also appears that your question is answered in the FAQ[1]:
"Why can't I post a comment to a thread?
"Threads are closed to new comments after two weeks, or if the submission has been killed by software, moderators, or user flags."
[0] https://news.ycombinator.com/newsguidelines.html
[1] https://news.ycombinator.com/newsfaq.html
And yes, submission history noted.