Why is it okay to assume that for E, even if Azedcorp is forced to sell, they WILL sell to Morris? What is the boundary of assumptions made, especially if B is wrong for arguable assumptions as well?

I see a lot of confusion on why there could not be an assumption such as a "third option". For example, the third option could be stealing or through a different program. In my opinion, this is irrelevant. If you recall, an assumption is a "missing link" between existing premises and conclusions to validify the argument. Taking the existing premises, there is no "hole" per say in how these rules and facts can result in the conclusion.

If we were to modify premise #3 and say something like "Other members can prostrate themselves [...]", which omits "all other" and "must", then it would be reasonable to bring in an assumption on how else Walt could get the DVC. The "all other" and "must" limit the requirements to only the two presented.