> FWIW, Heap would automatically create new tables for customers as they sign up and would also automatically create new indexes for customers as needed. For that reason alone, I'm pretty sure Heap would violate the Timescale license.

Nope! The user doesn't define or control that those tables and indexes are created. I.e., the user, through the Heap UI, doesn't say: I want a table with this schema and I want to create an index on (event_id, timestamp).