It is not ambiguous. Ambiguous means that you cannot tell the correct way to interpret it. It would be open to more than one interpretation. But the context here in this chapter defines the interpretation. The context is the comparison between the Mosaic patterns, and the heavenly Christ, who is the substance of those patters. Under the law, when things are said to be redeemed or purged with blood, there is no ambiguity. We all know what that means. It means that the principles of the pouring out of blood, symbolic of the pouring out of life are recognized, and then the item is recognized as "purged" from the uncleanness of sin and death. With this being the context, anyone who cannot see the same thing in Christ redeemed by his blood is simply trying to introduce ambiguity where none exists to avoid the reasonable conclusion.