Your job isn't being a courier, so it isn't in jeopardy.
I've never stated what my job is or isn't. I will happily admit while swearing on a stack of bibles that my job has absolutely nothing to do with providing any PR for the company here on this board or anywhere else. Other than that, you're on your own.
Maybe I'm a courier. Maybe I was at one time. Maybe not. Maybe I'm an ops mgr. Perhaps a senior. Could be a non-exempt position somewhere in the company. Maybe an exempt position. Might be a material handler. Flight ops, maybe? Better yet, I could be one of the guys who helps develop packaging. An accountant! Or not. I might be a tiny cog in the facilities department and all I do is staple purchase orders to invoices. Might I be involved with district management? I might. But I might also be a ramp agent or a handler in a hub. Then there are the other possibilities! Maybe I don't work for FedEx at all. I might have a friend who does and he tells me things and I post them here for the heck of it. Or it could be that I'm also one of the other posters on the board who doesn't agree with me and under that persona I post a bunch of anti-FedEx stuff that isn't true just to stir the pot and get people all worked up.
Have you ever considered the possibility that the company leaks certain things to certain people to see which things pop up on this board so that they know who's blabbing?