Vow of Silence, 1-second spells, and the AI

This isn't really about heroes but it says AI here so I guess I will post here.

Is there some deciding factor to whether or not an opponent will cast a spell through the 1 second that Vow of Silence is inactive? Sometimes on Shiverpeak Runs I will get hit by Mindfreeze or something in that second, yet other times nothing happens and I just recast and resume. Now I thought that with the AI's godly reaction times (they interrupt 3/8 and 4/8 casts consistently...) they would be able to squeeze a 1-second spell through 100% of the time the millisecond that VoS falls off, but... idk. Is there something that makes them reluctant to cast after getting a message saying "Target foe cannot be the target of spells" repeatedly and giving up?

I would think that the AI was probably wanding you when that 1-second time frame occurred. While wanding you can't cast spells...so that's probably it.

lol use a +20% enchantments scythe..