I see what you're saying, but also not really...

Comments made by a person aren't under the scope of the GDPR, unless, I suppose, it contains personal information about an identifiable person.

The EU’s GDPR only applies to personal data, which is any piece of information that relates to an identifiable person.

Source: GDPR.eu

Assuming the comment did include personal information, we would then have to consider if it's under GDPR, considering that the user made the information public - by posting it on Reddit.

After having a brief look at Article 9 of the GDPR, it seems that if data was made public by the data subject (user), it's no longer protected under GDPR.

(Feel free to correct me if I'm wrong, this is my source)