administer nodes overrides view restriction (logical somehow, but...)

i created a calendar and basically two roles:
the site owner and his supporters

the calendar should include public, internal and private dates of the site owner (done by taxomomy for dates)

my task is now to make the private dates only visible to the site owner AND have the possibility for the supporters to manage nodes (thats how they should support).
everything works nicely so far, guests see the public, supporters the public and internal, and the site owner all dates.

but when granting "administer nodes" to the supporters, the calendar view then shows the private dates as well, only the colour label above is missing.

is there any known way around this? to let roles administer nodes, but still provide some privacy on certain tagged nodes for the site owner role?

any hint would be appreciated