You own the content of your tweets. But you don't own the instance of the tweet that is stored in Twitter's database. They are are under no obligation to make it easy for you to save them ex post facto.
If you want to archive / cross-post your content you need to store it some place that you have ownership over. Whether than be a word document, spreadsheet, open source microblogging software, or whatever else, you shouldn't expect a media/advertising company to provide CMS features, that's not why they exist.
Comments
You own the content of your tweets. But you don't own the instance of the tweet that is stored in Twitter's database. They are are under no obligation to make it easy for you to save them ex post facto.
If you want to archive / cross-post your content you need to store it some place that you have ownership over. Whether than be a word document, spreadsheet, open source microblogging software, or whatever else, you shouldn't expect a media/advertising company to provide CMS features, that's not why they exist.