USE_RC_SUBR implicitly adds the script to the end of the plist, affected by @owner and @group. This invites some foot-shooting. I noticed an rc.d script owned by the daemon it controlled. I added a patch to PR# 218179. Then I asked myself if modifying the operation of USE_RC_SUBR to avoid this happening might be a better solution. At the bare minimum the appropriate page in the Porter's Handbook deserves a note. I don't have patches provided for any of that, I'm sorry. I don't know that portlint does or doesn't check for this issue. Still though, even if it does, any hypothetical reason that the rc.d script have an owner besides root (and i can't think of a valid one without going very contrived) should be equal reason to point it out to the user during the install process.
Tentative patch in D25295
A commit references this bug: Author: mat Date: Thu Jun 25 12:37:26 UTC 2020 New revision: 540386 URL: https://svnweb.freebsd.org/changeset/ports/540386 Log: Make sure rc files are owned by root:wheel with a sensible mode. PR: 246158 Reported by: Chad Jacob Milios Differential Revision: https://reviews.freebsd.org/D25295 Changes: head/Mk/bsd.port.mk