The title question says it all, pretty much. This is in the Walrus’ normal habitat, with an unlimited supply of matzot.
In their natural habitat, walruses eat a lot more protein and, <ahem>, seafood. Matzos are mostly made from flour and contain a comparably small amount protein, to say nothing of the B vitamins, minerals and fat content that a walrus needs. Their tusks’ similarity to a clam rake implies rooting in the ocean bottom for clams, worms and snails (their diet of choice), thogh the importance of clams in the Walrus diet has probably have been overestimated .
My WAG is that a low protein diet of only Matzo would be fatal for a walrus. Eating only Matzo, a walrus would die in 2-6 months, if nutritional supplements were not added. YWMV (Your Walrus May Vary)
So much for kashrut.
Planning an interesting seder?
A long time. 
Next year in… okay, I’ll bite. Where did you get a Jewish walrus?
The time has come, the Walrus said, to speak of many things…
Animal linguists have recently discovered that “Goo goo ge joob” is Walrus for “Enough with the damn matzo already! Bring me some clams, worms, and snails!”
OK, I’m really curious. What prompted this question?
No Gefilte fish?
Barbarian!