SCTP associations can’t be transparently proxied,
Also MME contexts would need to be synced between vMME instances.
This means if you have Keepalived and two MMEs behind it, and you switch from one to the other, the new MME does not have the context so would need the sub to attach again.
The best course here is to use MME pooling / S1 Flex on your eNBs to connect to a pool of MMEs in active-active form.