Trump's family being on the board is alarming for another reason. There are several markets about the president's actions that often involve missiles.
These venues do not have enough liquidity to attract Trump and his cronies. There might be people lower down the food chain who are taking advantage though.
If the goal is to profit off of bombing other countries, why do you need Kalshi?
If you have advance knowledge of an attack, there are much less conspicuous ways to profit off that.
If you are referring to Polymarket, it's an advisory board, not a board of directors. Big difference.