It was (after porting to DEC's simpler paging hardware and purchase from BBN in 1973), but if that's not what your comment referred to, then what?
First, the SAIL PDP-10 didn't run TENEX. SAIL maintained their own operating system based on the PDP-6 Monitor, called WAITS. I guess you could say its closest relative might be TOPS-10; certainly many programs could easily be ported over back and forth.
Second, as noted here, TENEX was not "later called TOPS-10". It also wasn't called TOPS-20. DEC took TENEX, and with extensive modifications and updates produced TOPS-20. Meanwhile TENEX continued to be developed and maintained separately at sites that elected not to switch to DEC-20 machines.