Two things seem evident...
These Ram coaches can make quick decisions and seem unwilling to "settle" on players. I admire and respect that after 10+ years of Ram mediocrity.
They must be pretty happy with what they've seen from their other DL candidates.
Both things seem like positives to me.
As an aside, I wonder if it's something Walker lacked other than the physical side of the position? Football smarts, conditioning or effort, meeting participation, interaction with coaches or other players, etc?
McVay loves to pop unexpected questions at players and coaches during meetings, for example. Walker (or some of the other early cuts) might have been guilty of shortfalls in some intangibles. McVay strikes me as a HC that places great importance on such things.