J doesn't have LOS to the Zombie because the line pass through the space of the zombie and the rules explicity doesn't allow that. The LoS is traced by corner to corner, and if there isn't any obstacles (including the edges blacks of the tile, treated as obstacles), the LoS is blocked.
Yes, the rules are quite clear about that. It's just that a lot of people (myself included) don't particularly like the idea that the very figure you're trying to attack can block your LoS to attack it. Hence the debate.
I think it's easy enough to house rule these little corner cases for people who can't live with RAW. Everyone can have their fun in their own way, provided of course, that the people sitting around the table can all agree.
I agree with you but i think that hourules some aspect of the game would be results in an unbalanced game. I think that the movement of giant monsters is much worse, but after several games I can say that it works, especially for the fact that most of the scenarios have victory conditions that involve a high degree of mobility on the map. A giant monster can block or be blocked resulting in a stalemate that is not expected in the development of the scenarios. Changing the rules to make them more realistic could result in a deadlock that is not contemplated in the development of the scenarios. For example, a giant monster can block or be blocked more easily by using a different movement similar to that of the first edition, resulting in a lengthening of the game and in a substantial change in the gameplay imagined by developers.