If using port forwarding, the only way you can affect this is by only allowing certain IP addresses.
The Aruba Switch likely has systems for authentication/authorisation (e.g. local users, RADIUS etc.) and it would need to be implemented there.
If you were accessing the Switch via VPN through the MX instead, you could use group policies to lock down SSH access via user. Port forwarding does not have any sort of functionality for user based policy.
Whilst I am a Meraki employee, some of what I post may be opinion (especially architecture!). Others may have better or more efficient ways of doing things, so please learn from everyone!