What does "50 ohm system" mean?
What this language is telling you is that these devices can be used in distributed impedance systems.  There are two rough areas of analysis, lumped and distributed.  Distributed system use the wave equation to describe them, are typically built using waveguides, coax and strip lines etc. and operate with characteristic impedances. Lumped systems are modelled as collections of  R,C and L's.  There is also a division between high frequency and low frequency ( and those cut offs have different meanings to different people) but around 10's of MHz is normal for the lumped vs. distributed model.  Low speed being the domain of lumped ...

Basically those parts can be used to switch high speed signals using coax etc.  that means you're safe to use them at your slower speeds.  You might be paying for performance you don't use but it will work nevertheless.  At the slower speeds you won't need to worry about 50 Ohm termination and reflections etc.