From my testing, after casting a scroll of anti-magic, the cleric is able to use a spell from his tome. Not directly, the tome will not open, but quick cast works normally, even though it shouldn’t. (It shouldn’t, right?)
Game version: V3.0.0. - BETA - 2.7
No worries, it’s not a big deal either way. It used to be an important rule back on the PD subreddit when releases were a lot buggier, “I found a bug, evan pls fix” posts would take over the subreddit sometimes.