Yes, Alert Logic® scanning (Cloud Insight™) does support excluding instances from being scanned by adding them to a whitelist. On the Topology page, you can define a set of tags that, if present on an instance, will be excluded from scans. You can search for tags by key or value.
Possible implementations or uses for this include targeting individual hosts by searching their “Name” tag and adding them to the whitelist one by one. It is also possible to whitelist multiple hosts by tagging them in the AWS console with the same key:value pair selected to represent whitelisted hosts (such as status:whitelisted).