It definitely can happen, it is a vulnerability but an acceptable one:

1. There is no such thing as perfect anti-cheat solution with today’s resources. Even client side rootkit based solutions can be overcome.

2. My solution completely eliminates wall hacking at 90% of the cases, same can’t be said for the rootkit anti-cheat solutions.

3. Game can be designed to put corner campers to disadvantage. But honestly no need to think extremely deep about such cases, you would first release the game then check the player complaints about wall hackers. If it is a major issue then you can implement a double ray-cast solution for most reported players, use correct size wall for their ray-casts and ban them statistically. Even if you can ban players accidentally it wouldn’t be a huge portion of your player base.