The number of generals (and admirals) in active duty is capped at about 650. Active duty generals are prohibited in most instances from opining in political matters, and they almost absolutely refrain from political matters over which they are not prohibited from opining on. Even after retirement, most still refrain from public opinions on political matters, but a small subset become politically active.
109 retired generals is far more than you can regularly expect on ordinarily political matters. For context, nominations for secretary of defense generally elicit opinions from retired generals. James Mattis, who quite possibly is the most popular military general for several decades, only ever received a couple dozen public expressions of support for confirmation as secretary of defense. The fact that 109 generals publicly opposed any confirmation of a Secretary of Anything, let alone a director level position, and did so in a unanimous letter, is absolutely massive.
109 retired generals is far more than you can regularly expect on ordinarily political matters. For context, nominations for secretary of defense generally elicit opinions from retired generals. James Mattis, who quite possibly is the most popular military general for several decades, only ever received a couple dozen public expressions of support for confirmation as secretary of defense. The fact that 109 generals publicly opposed any confirmation of a Secretary of Anything, let alone a director level position, and did so in a unanimous letter, is absolutely massive.