Note that attesting on CLs A and B and proposing via CLs D and E is not currently supported by Vouch: It only has one submitter for everything. The strategies you see are actually selection strategies.
Jim McDonald had this to say about dDoS:
“Regarding DDOS, it isn’t so easy to stop a beacon node from broadcasting a single proposal so it’s more likely that an attack would attempt to overwhelm a node prior to the proposal, either through an eclipse attack or just DDOSing it a slot or two in advance so that the block it produces is ultimately orphaned. The way that Vouch could avoid that would be to have a node that is on the list of nodes from which it obtains proposal data, but not on the list of submitters. So there is always a “listen only” node that should be up-to-date when it comes to Vouch creating the proposal.”
This can be done in Vouch thusly:
Assume I have CL nodes A,B,C.
Use A,B for submitters
And A,B,C for all selection strategies
Even if A and B get attacked, C should still have the proposal ready, and keeping a node from actually submitting the thing is non-trivial