The Sith Temple Bench decoration can be dropped from Ultimate Cartel PacksWild Space Explorer's Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Ultimate Cartel PackWild Space Explorer's Pack, include a random selection of items from the Ultimate Cartel Wild Space Explorer's collection of items. You aren't guaranteed to get a Sith Temple Bench decoration from a Ultimate Cartel PackWild Space Explorer's Pack, but it is one of the few ways to get a Sith Temple Bench deco apart from buying it on the GTN from another player.
If you're looking to get a Sith Temple Bench, the easiest way to get it is to head to the Galactic Trade Network (GTN) in SWTOR and buy it with credits from another player. If it's very rare and not available on the Cartel Market, you could try buying from the GTN and hope you get it.
Contributors: Wild Space Pack