Good point
From the original DARPA proposal:
It is anticipated that Walrus will operate in areas where there is local air superiority and ground defenses are suppressed. Survivability will still be an issue that demands importance and will be shaped by the definitive needs resulting from the development of CONOPs.
Figuring out answers to your objections seems to be part of the design problem.
Once laser defense systems are perfected, something with an enormous payload might be an ideal platform for it.