I initially thought this wasn't the case, but did some research - so for posterity: if you overhear the information in a public setting you may be ok. It depends on whether you have a duty of trust, apparently, and personally I'd run it by a lawyer before firing up Robinhood. [1] Although (1) IANAL and (2) you may still be answering difficult questions if you structure your trades the way this individual did.
There is precedent that even if you are in possession of info that will eventually become public, which you then trade on, you can still be convicted of insider trading.
For example, a Printer for Business Week and a Stock Broker traded on pre-publication information and were convicted of insider trading.
> for using stock information in “Business Week” magazine before it was distributed to the public
They traded on information that was non-public at the time of the trade. Why shouldn't that be treated exactly as trading on news of this merger before it was announced? (The merger was eventually going to be known to the public as well, right?)
[1] https://money.com/insider-trading-examples/