Hello Brian
In EIGRP just like in OSPF, it is possible to set the default state of an interface as passive with the passive-interface default command under the router eigrp configuration. This is explicitly explained in the OSPF passive interface lesson found below, but not in the EIGRP passive interface lesson.
I will inform Rene about your suggestion to add it explicitly in this lesson as well.
I’m very pleased that you find this forum useful for you in your studies and your endeavors to obtaining your CCNP and beyond. We’re glad that we can be of help!!
Laz