Logically, no one who is going to ignore someone will do this, but:
Imagine that I have a user being "followed" by the bot. And later I "ignore" the user on the forum, what will the bot do? Or I "ignore" a user on the forum, and then it comes to the bot and I request to "follow" that user, how does the bot react?
I believe in both cases, the bot still notifies you because It accesses no forum data, so it doesn't know if you ignored the user via the forum or not. All it does is scrap forum posts.