Sure. The merger, like any other merger, has stipulations. None of those are violating any sec regs. But the merger document has several options. One of them would basically be to leave things status quo. But he can't "guarantee" that one of those options ($15) will be the one chosen and then chose the latter or alternative.
Even if he says that their intention was to chose one over the other but in retrospect they evaluated the circumstances and chose a different option, the fact that he guaranteed something publicly is a violation of securities laws. If I, as an investor, bought based on the guarantee and then it was changed, it's grounds for a civil lawsuit aside from sec enforcement.
Even in tort law, there's basis when someone offers a guarantee in exchange for monetary consideration.
The most valuable commodity I know of is information