Sentence Correction

As per the modifier rule we need to put comma (,) between non essential modifiers and their nouns .

Ex : A discus, a circular metal disc , is used in Olympic games .

The phrase : a circular metal disc - in this case an appositive is non essential modifier and is correctly enclosed by commas .

Now can we apply the same logic in case of subordinators .

What I mean is can we rule out a SC option purely because a subordinate clause is being used as a non essential modifier ?

OR

Is it correct to use subordinate clause as non essential modifier .


Here are a couple of examples these are OG 12 examples :

1.Seldom more than 40 feet wide and 12 feet deep , but it ran 363 miles across the rugged wilderness of upstate New York , the Erie Canal connected the Hudson river at Albany to the Great Lake at Buffalo , providing the port of New York City with direct water link to heart land of the North American continent.


Although the sentence is incorrect and has other flaws .

But if you see the clause in green is marked as nonessential modifier and it is a subordinate clause - is this correct ?

Can we use subordinate clause as nonessential modifier ?


Another example from OG that has a similar pattern.

2. Defense attorneys have occasionally argued that their clients' misconduct stemmed from a reaction to some thing ingested , but if criminal or delinquent behavior is attribute to some allergy to some food , the perpetrators are in effect told that they are not responsible for their actions.


This sentence is correct and again if you see the clause in green is a subordinate clause and is non essential modifier .

So is it grammatically correct to have subordinate clause as non essential modifiers .

If not then what is the rule ?

Can any one throw some light ?