Please note the article relates to network ports used for SSL interception (inline/TAP) or device ports connected to an appliance doing inspection of decrypted SSL traffic, not the SSLV device management port.
SSLV management port has a configurable MTU using network set mtu CLD command.
SSLV is a transparent device and does care about MTU on its network/device ports. MTU is not configurable there.
However, SSLV can only inspect standard ethernet frame sizes - up to 1500B. Larger frames will be cut-through. This feature has been in place since 3.7.0 version as stated in the SSLV Release Notes:
Basic jumbo frames support; jumbo frames now cut through, so you no longer need to redirect jumbo frame traffic to avoid corruption.