Certainly if one does "without dbus" whole desktop build and it's operational, the board and the community will benefit from that kind of a procedure.
Regarding your main concern
Security vulnerabilities related to D-bus Project : List of vulnerabilities affecting any product of this vendor
www.cvedetails.com
The most serious vulnerability was discovered 10 years ago and it allowed information disclosure and denial of service. A local exploit without any privilege escalation consequence.
I believe that this discussion is moot. It was an official handbook procedure to enable dbus in rc.conf for FreeBSD for several consecutive releases in order to have operational X11 desktop.
What is the security status of all the installed non-dbus applications? Have they gone under such a scrutiny that dbus seen in last 15 years as integral component of *nix desktop? Has that scrutiny resulted in less than impressive (from hacking standpoint) CVE log? What spawns in your processes during your entire runtime, has everything been CVE checked in such a manner that dbus is left as the Pedro and the most suspicious component?
Again I'm not trying to demotivate anyone but show my viewpoint. You need to find a sweet spot between security and functionality. You need to take a good look at things and set aside those that do not concern you.