Even though Kardashian and Thompson are officially off-again in their on-again, off-again relationship, he did not take too kindly to seeing Odom's message, replying, "God brought you back the first time. Play if you want, different results."
The threatening message was clearly a reference to Odom's near-fatal O.D. in 2015.
Thompson, the father of Khloé's 3-year-old, True, also recently left a sweet comment for his ex under a snap of Khloé in a body-hugging dress.
A source tells People that in spite of the flirting, Khloé "is single and seems okay with it." They also assert that she is "very loyal to Tristan."
Khloé and Tristan first went public as a couple in late 2016. The week she was due to give birth to True in 2018, a story dropped about Thompson's infidelity. They broke up, but have been back together twice since.