So is the problem you can't walk through it? Because i can walk through it just fine. Or is the problem that since the polygon is set and i am guessing your player has his collision event set to dieing when he hits the model he dies.
If he cant go through it you can adjust the players hull manually.
If he can go through it but it triggers his collision event every time he hits a side then i don't really know sorry. There would be a couple things you could try like changing the collision type. Say if your using EVENT_IMPACT get rid of it and just use an event and just do a
instead of doing both entity and block. I could fool around with your script and try a few things but couldn't promise anything. Never really ran into a problem like this.
Sorry i couldn't be more of help.