I mistook "inside the rim" as being into the shallow drop down area of the rim on the tire/tube side (and less visible) but that is the outside of the rim whereas you are speaking of inside being towards the hub (and more visible); that side would also not have concerns about centrifugal forces causing them to come loose. My mistake.OK.
First, Big Ed. The button heads are inside the rim so Texas John is correct, in that the forces would tend to push the buttons into the rim. I will also tell you the first one I did stuck out too far so after a couple of days I decided to take it out and change it for a shorter one. Had to beat the (*&&^ out of it to remove it, So NO I have absolutely no concern whatsoever....
PS, I'm not the first person who has done this.