I stumbled across this today and I remember someone asking about it so I thought I'd post what I found.
Go to the following location:
\Program Files\Symantec Endpoint Protection Manager\tomcat\webapps\ajaxswing\WEB-INF\ajaxswing\conf\
Right click on default.properties and remove the read only attributes.
Stop the SEPM service.
Edit the default.properties file in notepad
Change the following line:
router.sessionTimeout=900
Set the default.properties file back to read-only and restart the SEPM service.
Adjust this value to however many seconds you want to allow the session to stay open. (900 seconds / 15 minutes is the default) I tested this just by setting it down to 60 seconds and sure enough, as soon as I did this the console would timeout after 60 seconds. There are other settings in this configuration file that appear to adjust the refresh rate and a bunch of other settings. I have no idea what kind of performance impact this would have. Try at your own risk.