Create a computer exemption policy.
Microsoft BitLocker Administration and Monitoring (MBAM) enables you to exempt users from BitLocker Drive Encryption requirements.
This makes no sense - users are not encrypted, computers are encrypted. We need a way to exempt a computer from encryption, regardless of the user logged in.
Jack Fetter commented
You can already do this; simply create a GPO with the opposite (disable) settings as your existing MBAM GPO and apply AFTER (place higher in the list of applied GPO's for each applicable OU) applying the standard GPO. This new GPO is assigned (filtering) to a new AD Security Group (name it something like "BitLocker Encryption Exclude") populated by the computer accounts that you want to exclude. These machines will then be exempt from MBAM encryption policy and/or decrypt if already encrypted...