Why can't 100% Disabled Veterans fly on Space A ?

It should be known that legislation has been introduced by Congressman Heller of Nevada to allow travel for 100 percent total and permanent disable Veterans to use Space A travel.
Many of our Service Connected Disabled Veterans who have been rated 100% Permanent & Total, who served our country and were honorable discharged. Have been passed over and DENIED, the benefit of the Space A Flight Program and the use of these available seats while the category list of eligibility has grown to include DoD Civilian employees, Contractors, Boy Scout Leaders, USO Athletes & Entertainers, Jr & Reg ROTC cadets, teachers, foreign military, the media, nonprofit organizations, and so on. The list is just endless of all those who have been extended this benefit over the years, which mind you, many or none have ever served in the U.S. armed services.
Often many of times these aircraft are flying with most of the seats empty or unoccupied.

It’s time to stop talking about helping Veterans and a start in the right direction would be amending DoD 4515 13-R to include a Category 7 eligibility for our P/T 100% Service Connected Disabled American Veterans. In an effort to support those Veterans that are permanently and totally disabled this benefit could be provided to them at minimal cost by the DOD.
Thank you,

It has to do with aircraft and passenger safety. Most military aircraft are not equipped to handle passengers that need assistance. Very few, if any, AMC terminals have jetways and passengers must be able to board the aircraft through sometimes small access portals and ladders. And as mentioned by PO1 William "Chip" Nagel, navigating the ladder to the passenger deck in the C-5 can be a chore.

I thought there was always spaces offered to vets if there were no currently serving soldiers asking for the spot. Did this change?