on the question of 'right to maintainership'

[personal opinion, since I saw no replies yet and I think this deserves one]

A LIR is responsible for the registration of address space assignments 
from address space allocations it receives from the RIPE NCC.

 From this alone it follows that a LIR may reserve the right to make changes
to these registrations. Of course the LIR should be responsive to requests for
changes. This does not mean that it has to make any change requested.
Changes should be goverened by a local policy.

Daniel

PS: Technically speaking you can have multiple maintainers on an object that 
all have equal rights. So if you trust someone you can let them make their
own changes while keeping the possibility to make changes yourself.
The right notify options will make sure you know abut changes.
Beware: Technically speaking one of these maintainers can remove the other,
albeit not without the other noticing if notifications are configured right.