(The following assumes "front-end" actually means the Arc source code that runs the back-end. The front-end is HTML/CSS/JS and therefore already open source.)

I'd personally rather it stay closed.

This is a mostly a simple site, except for the spam-prevention logic. Even that logic probably wouldn't be that interesting, because it'll mostly be against generic techniques (which are well-studied) and specific techniques (which aren't applicable to my own projects).

If the spam-prevention code were removed before publishing, what would be left is an incredibly simple "comment/post/list" type of site, which are just thin interfaces between browsers and databases (or should be...)

It would be interesting to see an Arc code base, but there are similar languages with more active communities to look at, if I want to scratch that itch.

So the upside is pretty small for me, and the downside is that it would give spammers a list of all the chinks in the armor. That could ruin the site.