Well, I don't exactly agree with your solution, but your point is well taken.  I expect to have content I syndicate available on the schedule I dictate for my site.  The internal syndication with DNN isn't good at all, and I touch on the subject in my blog,here.  I've discussed the need for a completely different method for syndicating content with folks ove the last year, and we're pretty much in agreement that IsSearchable IS not the answer.  It really doesn't perform well for using in queries of site content, which is what it was supposed to do anyway.  Syndicated content usage is more sophisticated these days, than what the IsSearchable method allows.  What is needed is an IsSyndicated method that stores information in a structure that give more flexibility and granularity. 

But... I've said this all before.  Read through my blog if you want more.  At this point, I'm tinkering wih the Announcements module to add capability to it to use as a way of creating news content.  The other possibility, I've worked on is providing syndication support for all modules by adding a SyndicationSupport panel that can be integrated into modules.  The biggest problem with most modules is they really aren't suited to use a syndication creator, and do not have the necessary fields within their tables to store the information needed to build a newsfeed.  With most implementations, you wind up having to compromise and match existing fields to rss or atom elements that do not really contain the content in a feed to best advantage.  So, the problem is more than just the IsSearchable method, it's one of a lack of design within most modules, whether they are DNN standard modules or 3rd party modules.

While I continue to address the need, it's not possible to provide to others until we know what changes are happening in the new Cambrian release,  where I understand some of these issues may be address.  Anyway, for what it's worth that's my spin.