There was a thread about this before in the IM Gateway forum. There’‘s no way as far as I know that the plugin could cause something to be in a non-offline group when the client is supposed to be handling grouping offline contacts into said offline group. In other words, the plugin has nothing to do with the group named offline. It’‘s not a real group, it’'s a pretend group created within Spark. At most the gateway plugin could be putting the contacts in a group called Offline, but that would look different in the Spark interface (at least based off my understanding of how it displays things) I have no control over said offline group. =/
Now, if said contact is showing up as something other than unavailable, that would be my fault. =) So is the contact indeed showing as unavailable, just not properly grouped?