The answer to your question is no...at least not any way that is easy.
The Marine Corps spent a good deal of time and money to find and begin the training process. In the all volunteer military of today there is no "easy" way out.
For good reason.
SOI is tough training. The Marine Corps historically looses a fairly large percentage of kids at this stage of training. The last thing they want to do is make it easier to get out.
There are ways out. But none of them good.
For example...some Marines
will "refuse to train"...at some point this will lead to a discharge
, though not with a good characterization.
Other Marines will leave
for several months then return. This will lead to discharge, but again, with a poor characterization.
So if the question is; "is there any way to get out" then yes...he can commit misconduct...and at some point they will release him from the contract, but only after rendering a less than honorable discharge
...and you want to avoid that.
THere are other avenues, for example if he has an injury that prevents him from training? That can be a path. But what you describe that dos not seem to apply.
Or if he has a deeply held belief in a spiritual power that precludes him from participating in the military, he can claim conscientious objector status. There is a process that allows discharge.
And if he has a mental health condition that makes him a risk for suicide? That also would lead to discharge. Though it is not clear from your description that this applies.
I wish you could convey to him that SOI is temporary in nature...it gets easier when he completes it and transfers on to his unit.
And if you have fears for his life, I would urge you to contact his Battalion Commander
...they can take steps to ensure his safety. Yes...it can delay his training. But it can keep him safe as well.
Let me know if you have more questions....happy to assist if I can