I've been TDIU for about on year, I know I can't use VOC rehab and I'm terrified to apply for my GI bill because I believe they will cut off my pension. I was thinking of Barber School.
Well, I don't know that you should be terrified. That seems to be just a bit of an overreaction. And, you don't have a pension. You're rating of TDIU is a disability compensation award.
Let's say that you were approved to attend a barber school. If you did well and graduated, you'd want to find a job or maybe open your own shop. You'd have an opportunity to work and learn if you could tolerate the activity and while you did that, your TDIU money would continue to come in so you could pay your bills and so on
Then let's say that within 4 months, you discovered that you couldn't tolerate the work because of your service connected disabling conditions. Your TDIU would still be in place and you'd know more about the limitations of your physical condition.
On the other hand, you might discover that you could do the required work and that you enjoyed it. Not only that, you may learn that you're making more money than you would receive through TDIU.
If you were able to work, you'd have to notify VA of that fact and yes, you would lose the TDIU benefit.
We have to recognize and accept that we can't legally or morally double-dip. The TDIU benefit is awarded to us because we can't work at "gainful employment". If our condition improves or if we find a job we can do, we are no longer unemployable and we aren't qualified for the TDIU benefit.
Is all that terrifying? I don't think so. Most TDIU veterans would jump at the chance to be employed if they could.
Go for it.