Let’s imagine the baby Gorn start off the way you describe, a perpetual small hunter that also produces more offspring. As they age they get bigger and stronger before they finally die.
The adults who take care of their offspring have an advantage over adults who do not care for their offspring, and possibly even more over the babies who never become adults.
There is another selection barrier as well. If all you have are baby gorn, what happens when you run out of hosts? This can easily happen if the hosts are over-hunted. If baby gorn pop out and there are no hosts, and they die out in a few years or even months, that’s an evolutionary dead end. The ones which can last a long time until new hosts are available will eventually be selected for.
In the end a contract is only as valid as the enforcement behind it.
Between two people of the same nation, a court willing to say “Yeah that’s valid” and enforce it with the power of the state makes a contract quite powerful.
Between two entities that cannot agree on a means to arbitration, or have that means enforced on them, it’s basically only as valuable as their willingness to accept it.
“A contract is a contract is a contract… but only between Ferengi” might seem like a straight up dismissal of another’s species rights to be negotiated with, but its also a warning. If the Ferengi authorities don’t have the power and will to enforce your contract with a Klingon living in free space, then a contract lacks the enforcement clauses that make it absolute.
So how binding is it? As binding as the parties allow it to be.