These two opcodes are unnecessary as the same functionality can be achieved via using nLockTime in an offline transaction.

If wanting to create a transaction that is valid on 1/1/2021, simply create an offline transaction with nLockTime equal to then and do not broadcast it to the network. This transaction can be stored in a trust, deposit box, or the raw TX encrypted on-chain.

Additionally, multi-signature requirements can be added for trust among multiple parties.

See the following blog posts for further references and explanations on how it can be done w/out the custom opcodes:

https://medium.com/@craig_10243/why-the-protocol-is-set-7db4f764c97c

https://medium.com/@craig_10243/why-cltv-was-a-bad-idea-4b5d0c043e2a

Satoshi’s explanation on why CLTV is unnecessary and how we can achieve the same with nLockTime:

https://nakamotostudies.org/uncategorized/hearn-and-satoshi-correspondence-part-5/