Good call and welcome to the site Get... I can't even type your screen name let alone say it

Regarding those little pins, their function is similar to the hand-in-jar method of trapping a monkey illustrated by this neat video:
For another example, the method of coupling a control rod to its drive mechanism in BWRs is also very similar. It uses a 'coupling spud' (See Item 46 in Fig. 2B in
this pdf). The fingers, or splines, of the coupling spud are compressed by a grooved opening in the
socket at the bottom of the control rod. Once fully inserted into the socket, they expand back out allowing a spring-loaded plug to insert down inside the splines. The plug then prevents the splines from contracting and lock the spud in place in the socket. A rod (Item 48 in the same Fig.) is used to push the plug up out of the spud to allow de-coupling. Fig 1A in
this pdf shows the plug (Item 14) inserted into the spud. (Too much info ...?)
Lastly, I've noticed that if you drop one, they apparently vaporize on their way to the floor. You can get several replacements
here for $6, or
elsewhere for $2.50 a piece (Honda's recommended price!).