I'll be the heretic here, but so far as I know you are only required to make source available when you distribute binaries. And for that matter, it doesn't even have to be online just available upon request unless you're using a derivative GPL that added online access as a clause.
I highly doubt the users of a web interface are required to be given access to source. There are multiple GPL-licensed web servers (I am well aware Apache is not btw) and I've never seen one embed a code link on every page.
Tl;Dr: Lemmy does it, but I believe it's not required. Modify away if you so choose.
rm -rf /home/*
You need the directory for the mount point.