Actually, HexView is just help tool for pdb debugger. That is why there is that invalid memory checking.
What actually WOULD make a lot of sense is separating "read" operation from HexView, so that it can be used to view many other entities (e.g. files). Adding to RM, but I think it will get realized in next release cycle (where I would like to concentrate on theide, and I would like to be able to view hexadecimal files there).