The unit file we ship for NRPE is apparently a slightly-modified copy of Debian's, and includes from upstream the setting:

OOMScoreAdjust=-500

... which means that NRPE is made less-likely to be killed than other processes if the kernel OOM-killer kicks in. AIUI this is is normally something you might do for a high-priority production daemon which is known to normally allocate large amounts of memory, to help ensure the oomkiller goes after less-important tasks first (e.g. a runaway puppet agent or interactive shell command or stats daemon of some kind, etc). It seems kinda backwards to give NRPE checks this protection, as we'd rather have NRPE die than the services NRPE is monitoring?