It's a bit shitty that anyone would even think of doing this to begin with IMO, especially considering that mercury's harmful nature is no secret!

Mercury is otherwise found as a by-product of other processes, such as the burning of coal

Actually susprised that it's even viable to use a byproduct of burning something else as a fuel

Apollo Fusion [...] insisted that the composition of its propellant mixture should be considered confidential information.

Good thing it wasn't considered in this scenario. Racing fuel using nitrous oxide and whatever is one thing, but spraying mercury everywhere into the atmosphere with a rocket honestly sounds like a sick joke

"[...] It would give you a competitive advantage in what I imagine is a pretty tight, competitive market"

Launching rockets is a competitive market? TIL, I thought there were only a handful of companies operating with very generous margins