imo, bug.
However mostlike, is as intended, cause it's been like this for quite some time..
Just because it's been that way for some time doesn't mean it's intentional.
Also, Frogboy said on several occasions that the AI is supposed to play by the same rules as the player (at least on challenging and below). So, having such an obvious deviation from rules be intentional wouldn't make any sense. It has to be a bug.
