It's not quantified though. Also, it's pretty bad engineering practice to rely on implied risk; it's much more preferred to explicitly state your risk assumptions.

E.g., one of the problems with the Shuttle disasters is that the implied risk was understood differently at various levels. (Making numbers up here but directionally accurate) After the fact, managers thought there was a 1/1000 risk of catastrophic failure while engineers put it a 1/172.

The sub had already completed a few dives to the titanic and the CEO downplayed the risks in the texts that came out between him and a guy that pulled out. Taking both of those together I can see why a non-technical person might be taken in and therefore dismiss the waiver as typical legalese.