The VA has been subject to a huge amount of criticism in recent years over numerous systemic failures in their care of the troops being released from active duty after being in the sandbox of Afghanistan. They have a double-barreled reason to exaggerate diagnoses of PTSD. First, as I posted, that's the buzzword, so if they can diagnose more cases of it, they have "proof" to the Congress that they need more money to hire more people to handle this "epidemic."
Secondly, because PTSD is such a buzzword, that last thing the VA wants is for any veteran under their care to do something that might be attributable to PTSD without their having diagnosed it, and made every effort to keep him (or her) away from guns. IMHO the VA would be overwhelmingly supportive of any initiative to ban people diagnosed with PTSD from firearms ownership or use for life. They are paranoid about guns.