> Не то чтобы маркетинг, но можно сделать вывод, что де-факто стандарт нтп не поддерживает какую-либо изоляцию на фряхе.

Угу-угу.
Или же, что составители табличек особо не заморачиваются ...

> This document compares features and performance of the following NTP implementations:
> ntp-4.2.8p15
> Presence of the features was determined from the documentation, observed behaviour, and source code.
> Last updated 2020-10-08 14:19:05 +0200

смотрим
man mac_ntpd
> mac_ntpd – policy allowing ntpd to run as non-root user

DESCRIPTION
     The mac_ntpd policy grants any process running as user ‘ntpd’ (uid 123)
     the privileges needed to manipulate system time, and to (re-)bind to the
     privileged NTP port.
...
HISTORY
     MAC first appeared in FreeBSD 5.0 and mac_ntpd first appeared in
     FreeBSD 12.0.

https://reviews.freebsd.org/D16281#
> Make it possible to run ntpd as a non-root user, add ntpd uid and gid.
> This revision is now accepted and ready to land.
> Jul 16 2018, 4:46 AM

/usr/src/contrib/ntp/ntpd/ntpd-opts.h (на FreeBSD 12.2-STABLE)
#define NTPD_FULL_VERSION  "ntpd 4.2.8p15"

/usr/src/contrib/ntp/ntpd/ntpd.c

#if defined(HAVE_TRUSTEDBSD_MAC)
# include <sys/mac.h>
#endif /* HAVE_TRUSTEDBSD_MAC */
#endif /* HAVE_DROPROOT */
...
#  if defined(HAVE_TRUSTEDBSD_MAC)
            /* We can run as non-root if the mac_ntpd policy is enabled. */
            && mac_is_present("ntpd") != 1
#  endif

Такой вот "обсервейшн в сорс код"