Trying to suck the colossal spirit power stored inside by any lower grade would end up by detonating one's body out of overload.
In addition to that, the amount of spirit power in that storm was enough to let a thousand gold spirit masters step into the dark gold grade in just a few days! Not to mention many of them would end up at the mid ranks as well.
So, William had to wait, wait until he'd reach the gold grade at least. The higher his initial stage was, the better he'd end up at the end.
He also wanted to bring many of his guild's trusted and capable masters here to get the benefits as well. So, he decided to hold back his plans for now and retreat. After all, this process would take decades or even a century for that bear monster to achieve its goal.
Besides, everyone in the area feared this place, there was no harm in letting it and go away for now.
