If we agree that most OS vendors will probably ignore the copyright claim and keep using the current database, then one could put any newer updates into a "patch database", which clearly would not be under any prior copyright (and could be easily made available to everyone as the old database was).
So, I don't really buy your parable about how this will only affect future changes. If tzdata "forks", it will be between what old (possibly copyrighted) data is included.
Well, on the one hand, I agree with you about one source of forks being old data, although at least this is a relatively simple fork: those who excise the allegedly-infringing parts of the database, and those who do not.
On the other hand, I think you are completely groundless in your assertion that it can't fork over future changes. There could be multiple patch databases with disjoint changesets in them, with different software using different databases.
And it's not _my_ parable. It's my rephrasing of the FA, and the comments by the FA's author in his own comments thread.
