1 - They did not want citizens to know we had incursions into our airspace that our forces were unable to repel.
2 - The UFO crash/retrieval studies provided knowledge they wanted to keep out of enemy hands.
3 - They had strong evidence that the existence of ET would be super unsettling to some people, particularly the religious ones.
Your post is exactly what I have been talking about:
.Gov reacted emotionally and then created a rationale to justify their actions.
Humans do not act for “reasons”—they “reason” to justify actions they have already taken.