I'm not saying that is the intended reading here. Nor, that such a reading is charitable.
One of the things I assume when I writing on HN is that I can go back an edit what I wrote to make it better. "Don't forget to live life," might better express the idea. Finishing with "Get a life" after showing the overall intent might better express the sentiment.
Leading with "Get a life" means the reader reads with only their existing context and can reasonably apply standard connotation. It is normally a bullying phrase, and an author ought to expect it to be taken as such without doing a lot of additional work. It is no surprise that it puts people off.
Suppose the author's response to people being put off by the advice "get a life," is something like "well, that's their problem." That's exactly the connotation of dehumanization "get a life" has in US culture and a charitable reading is unwarranted.
I assume the phrase was used here in the most generous sense but that's often not how it will be received. I think it's more constructive to avoid the phrase and to express the sentiment in other ways.
Experience has taught me don't get caught up and lose that balance. Its a long journey to recovery after you have suffered both emotionally and physically.