Activity for nodes that have a specific taxonomy term

I'm looking to implement activity messages, upon node creation or update, that are tagged with a specific taxonomy term. Nodes without the term would not generate a message. I'm looking for high level assistance on the correct coding approach for this.

Right now I'm thinking of doing a standard node insert/update template, then using hook_activity_record_alter(). Since the nid comes along with the record, I'd run a db_query into the term_node table, look for the NID+TID, and if they match create the record. If not, bail on the creation of the activity.

Does that sound about right? Or would you suggest a different and improved method of doing this? Thanks in advance.