Brief Q&A On Tachyons (Brian Greene and Jonathan Barlow Gee)

original context:
https://youtu.be/9gAcHKraVWE?t=9762
@2:42:42 My question: "can tachyons (faster-than-light particles) actually be the force-carrying particle of gravity?"

""the gravitational waves propagation speed c_gw to the 90% credible interval 0.55 c (greater than) c_gw (less than) 1.42 c, where c is the speed of light in vacuum."" - https://arxiv.org/abs/1707.06101v2