Allowing force-push is considered an antipattern for Git, and generally best avoided. It's a safeguard against lost history and prevents data loss.
That aside, the comments are the history. Git is the wrong tool for the job. Why would you choose a generic version-control system designed for source code diffs & merges for the specialised task of chronologically-ordered comments? A database such as PostgreSQL is a far superior choice in just about every possible way. I admire your ingenuity here to make something out of what's available, but I respectfully disagree with this being a good way to capture user-generated content when there are better alternatives.
you mean other files will bloat the repo and slow down the performance? Yes it's a very valid concern, but this system targets personal blogs, which I assume had very few comment traffic.
> Git is the wrong tool for the job ..... A database ... is a far superior choice in just about every possible way
the same argument applies to Wordpress.
But most tech people are choosing static generated blogs anyway, and with git too. File system is the database.
And there are good reasons for that.
I still wouldn't put them into Git along with the rest of the site, that's a definitely no-no. A separate Git? Also no for me. Filesystem does seem viable on reflection, and I feel inspired to explore this now.