Wildcard identity-based encryption (IBE) provides an effective means of communicating among groups which do not have a well-defined membership or hierarchy pre-established, as may frequently be the case in dynamic coalition operations. The protection of group communication against compromised nodes is, however, expensive in that it typically requires frequent re-keying in the case of attribute-based IBE or voting-based revocation mechanisms, which can be problematic in multi-hop ad-hoc networks. In this paper we investigate the use of asymmetric communication links such as may be provided by unmanned aerial vehicles to provide efficient revocation mechanisms for small ad-hoc networks. Such link characteristics allow the efficient maintenance and propagation of blacklists as proposed by Saxena et al. and also enable the development of probability and plausibility metrics for revocation requests. We therefore propose a scheme for the distribution of group keys that requires nodes of the group to collaborate in order to obtain the group secret key. Consequently, untrusted nodes are hindered from communicating with other groups. This isolation from untrusted nodes allows to avoid or at least to postpone expensive node revocations which require the rekeying of the whole group.