I thought the rules were not, but the DBMM-commentary (Toby Partridge) were quite clear about this issue.
The element not yet in the TZ, can't move directly sideways because it reaches the TZ doing that, and is so restricted by the TZ-rules. But moving immediatly backwards, you don't reach, enter or starts in the TZ, so you don't have to follow the TZ-rules, so I thought it should be a free single element move, allowed every movement, except of course directly sideways.
The move I suggested should only be a problem when there is also a element directly behind the element that starts at 80p and it can't move back first. :'(