Does Android swap out memory used by foreground services? Looking at an Android KitKat device made by LG, I see that an app called Software Update is always running as a foreground service (100).  That service occupies a significant amount of memory.

From what I can tell, that app is just for OTA updates, which is an exceptionally rare event (has never happened so far!).

In order to free up some working memory, I was thinking about preventing the app from starting on bootup (by disabling its Broadcast Receiver), and then just running it manually once in a while to check for updates.

But before I do that, I want to ask if it matters at all?  For apps that are always running a foreground service, will Android simply swap them out of memory like a background app?  Or is the memory they use blocked off completely at all times, thereby making my plan worthwhile?
you said : 


  (by disabling its Broadcast Receiver)




First let me point out that Broadcast Receiver and Service is not the same thing ,you will get the difference between them along the answer.

Broadcast Receivers :


Quoting : Dianne Hackborn, a Software Engineer see Article Here



  A BroadcastReceiver allows an application to run, for a brief amount
  of time, in the background as a result of something else happening.
  When handling a broadcast, the application is given a fixed set of
  time (currently 10 seconds) in which to do its work. If it doesn't
  complete in that time, the application is considered to be
  misbehaving, and its process immediately tossed into the background
  state to be killed for memory if needed.


So as you can read BroadcastReceiver can't keep an app running in the background for more than 10 seconds kinda limited right ? that's why there is services.

Services :


Quoting the Same author from the Same article  :



  A Service allows an application to implement longer-running
  background operations. There are actually a lot of other functions
  that services provide.
  
  Android Process management for services is different than broadcast
  receivers, because an unbounded number of services can ask to be
  running for an unknown amount of time. There may not be enough RAM to
  have all of the requesting services run, so as a result no strong
  guarantees are made about being able to keep them running.
  
  If there is too little RAM, processes hosting services will be
  immediately killed like background processes are. However, if
  appropriate, Android will remember that these services wish to remain
  running, and restart their process at a later time when more RAM is
  available. For example, if the user goes to a web page that requires
  large amounts of RAM, Android may kill background service processes
  like sync until the browser's memory needs go down
  
  Services can further negotiate this behavior by requesting they be
  considered "foreground." This places the service in a "please don't
  kill" state, but requires that it include a notification to the user
  about it actively running like music players ,Anti-virus etc ...


The app need to show a notification ,in your case it's a System application it doesn't need this requirement it can tell the System that it needs to be running all the time and the System will not kill it only if the system needs more memory and it is the only service still running (What are the odds of that happening).

Now Going back to your Question Will it be worth while ? I think it is because it's a waste (truly a waste ) memory used and will not be freed ,for no purpose.

I will add : 

your plan to stop it's broadcast receiver may not keep the service in the background ,I would recommend you disable the app under Setting > application > all and click on disable (if that button is there ) or freeze the application using titanium backup.

Ref : 
http://android-developers.blogspot.com/2010/04/multitasking-android-way.html
http://www.howtogeek.com/161225/htg-explains-how-android-manages-processes/
http://developer.android.com/training/articles/memory.html