I love this option. Especially with it interacting with combat labels. A much more elegant solution that what I first proposed in another thread.
One benefit is that with something like this in place and documented, I think it would free up staff a little. If a player wants to set their @lp or @tp to something mimicking a mechanically significant message, go for it. Players will know it's RP only or maybe ICly the character pretending to do something.
The only thing I might add is that the system might need to be extended to cover other meaningful states that use @lp/@tp messages as indicators. Like sitting. Possibly diseases and medical bits. Staff would know better and, if something like this is implemented, we can catch and add such states as needed over time.
Or, possibly better, create a verb that that can be called by the game's code to set a players @lp/@tp/@sp that takes three arguments: the 'place version (lp/tp/sp), the message, and the state. Then find all code that sets lp/tp/sp messages and change it to use the new verb to set them. This might create some uniformity and catch most existing cases where using this system would be an improvement. This is just a rough idea though. DO with it what one will! :)