pstef@ pointed out that my change in https://cgit.freebsd.org/src/commit/?id=d6ae056e9dc96c2db45982ac358ba9ed716a9202 is no longer accurate.
The -p option does not imply -x, it is merely a different mode that ps uses. Remove that statement from the -p option, effectively rolling back the commit above.
He introduced the -D option in https://cgit.freebsd.org/src/commit/bin/ps/ps.1?id=5c0a1c15ff8cb66128f4826ace8ba91e0a31486d which also turns ps into a similar mode. List the -D option along with the others in the first sentence of the second paragraph of the DESCRIPTION for completeness and correctness sake.