Actually that rule is not new to LHTR 2.0, or to LHTR in general, or even to Revised.
That rule goes back at least as far as Second Edition which I first played in the late 1980’s/early 1990’s. It has consistently been in every version of A&A I have played and every rule set I have ever reviewed.
I know it sucks (I have had it screw me over before where I just wanted to get a BB shot in, the dice went south for the main land force, and I had to stick it out…) but that rule for amphibs being “to the death” has been around from the beginning of the game.