My interpretation of https://docs.aws.amazon.com/ses/latest/dg/creating-identities.html and https://repost.aws/questions/QUy_J6aNWOQGyfK25hGrEb8w/do-i-need-mx-record-for-only-sending-emails is that SES requires your to domain to have a valid MX record so that bounce-backs have somewhere to go, but it does not require that the MX record point to SES if you do not plan to use SES to receive email.