API credentials visible for every site on Multisite

Hi there,
i just noticed an issue on my multisite configuration using mailgun.
Placing the constants in wp-config.php (as described in your faq) and network-enabling the plugin to be used on all sites with same credentials, also makes the credentials (api key etc.) visible (/wp-admin/options-general.php?page=mailgun) for every sub-site-admin. that may be fine if you′re running severals sites for your own in multisite, but not for a SaaS multisite with external users or customers. Users may misuse the API key etc.
Please consider an option for multisite superadmins to hide mailgun credentials on sub sites, there is no need to share your global-multisite api key with sub-site-admins.
tnx, Eric