Reports from 2007/2008 had already indicated significant interference and government spying between agencies and with private corporations. Also, at that time it was widely believed but not yet confirmed Dual_EC_DRBG was backdoored via NIST/NSA collaboration.
Many folks equate any US government money with NSA money, and did so especially around this time, which is likely why you made this mistake. Taking any US-backed government money, even at the time Signal took it, was and should be suspect.
IIRC Signal continued to take money even after Snowden. So it is a fair point and not at all idiotic, and the over-reaction after you agreed to correct the article is suspect.
I do think Signal needed that money to survive, and it probably was put to good use, but I would have acted differently and more transparently about how my use of that money was communicated to the public.