Note that HN doesn’t support Unicode in comments, so plaintext emojis are the only option.
Some Unicode works here — like the preceding em dash and the hair spaces around it, along with bullets:
• One
• Two
The point might have been that with access to emojis (on other platforms) youngsters no longer use the oldschool emojis. Use of oldschool emojis strongly suggests oldschool poster :)
Use of the word "emoticon" instead of "emoji" would also be a strong indicator :)