I understand your point of view and we could go away and discuss implementation options for multiple devices, but it is kind of irrelevant to the problem at hand. The Servlet 2.5 spec, section SRV.7.1.4 states:
This support is already there for Shiro native sessions. It just doesn't work correctly.
I guess you could argue that this functionality should be removed rather than fixed. However, even if this functionality was removed from Shiro native sessions, the Shiro user would still be able to access this functionality by using Tomcat/Jetty sessions instead (as these containers are servlet 2.5 compliant)...so little would be achieved apart from hobbling Shiro native session functionality.