Flying is safe after a TBI. I have done lots of flying. The only problem you may have is over-stimulation from the constant low level vibration and sounds plus the visual clutter in a confined space. Plus airports can be very chaotic and over-stimulating.

I just plan for a quiet day after the travel day, especially if the flight is a long one.

Just plan to take it slow. You want to enjoy your time not spend it recovering from the stress of the travel.

My best to you.