Aziraphale didn’t give Crowley holy water. He would never give Crowley a suicide pill.
But it became holy water because Crowley assumed it was, assumed his Angel would never lie to him.
Which is why Aziraphale doesn’t bring up the ‘I lost my best friend’, scene.
He’s too afraid that Crowley had opened the thermos and attempted to drink it in his sorrow, and he couldn’t bare to hear that Crowley found out he lied.
