I don't think so. You specifically replied to a comment by calling it a "fallacy", when it was discussing feelings of parenthood. That's very specific and cannot be excused as arguing it was addressing the broader context of TFA. And the whole sub-thread
was about feelings.
Also, nobody here -- the people you're debating with, I mean -- is arguing that having kids is universally the most meaningful thing anyone can do with their life; they are instead offering their personal perspectives. For example, in the sentence you quote:
> Raising kids is probably the most meaningful and significant thing I have done with my life
The operating words are "I have done with my life"; it's not telling you what you should do with yours.
In fact, the whole debate in this sub-thread was sparked by a very aggressive comment (not yours), but which you chose to implicitly defend:
> You don’t need children to have these sorts of feelings, unless you can only get them from some small people who don’t have any choice but to love you.
Well, whether the person saying the above has or doesn't have children is entirely relevant. It's not a "fallacy". We're discussing feelings, even the above comment acknowledges it; and in relation to parenthood the fact remains: these feelings must be experienced, you cannot truly comment on them otherwise. I mean, you can, but your opinion wouldn't be of much value.
Read again the comment that prompted the above comment:
> What's so easy to miss is the immense feeling of love, of being needed, of being loved, that words can't describe. I frequently tell people I feel like the grinch after he discovers Xmas - my heart is three times bigger. But you can't really see that it's just a feeling I carry with me.
Really, it's all about subjective feelings. Which, essentially, is all that matters in the context of this conversation. If you don't have children, you won't have felt like this. You simply cannot. So it's not a fallacy to ask if you have them.
edit:
> a blog post that claims having kids is the most meaningful thing you can do with your life
The blog doesn't claim this, either.