loophole in army contracts?

every recruiter for the army will tell you all the time and even show you the part of the contract where it says that if for whatever reason besides yourself your job becomes unavailable you can chose an new MOS or chose to leave the army. One thing they dont tell you is that no matter how long you sign for, you are obligated to sever for 8 years if the army needs you.
They are using this rule to keep people past the date in which they where supposed to leave.

So take this hypathetical situation: Someone signs up in a position that requires top secret security clearance. And for some reason they say he didnt pass the background check though he believes he shoudl have. The job he signed for is no longer available to him, he now has the two choices from his contract; to pick a different job or get a discharge.

If he chose to get a discharge is he still bound by the 8 year obligation? Could they force him to stay in because of it?

that would be because they flunked out of the schooling though. im talking about something out of their control.

The 8 year obligation is a statuatory obligation. I will have to look at a contract later to see what exactly the wording of the release is. It may allow the person to enter the IRR. If this happens prior to basic training, the soldier is still obligated, but is not deployable without the requisite Initial Entry Training, so they are pretty safe in the current scenario, since a non-deployable soldier is fairly unlikely to be called up unless there is an incredibly dire need (WWIII type stuff).

That said, I am not sure what the contract says, so all of the above is a best guess. If I get a chance I will look it up.