Here is a link to the last time this was brought to the attention of the Adobe team on 9/11/2014: Safari Browser Tab Cleared After Flash Installation
Is this something that will be fixed soon or does Adobe just not care? It can be very time consuming to track down tabs that were left open for various reasons. Please fix this and have Safari re-open with tabs that were open before a Flash player update.
It's something that we're aware of, but it's not trivial to solve. It's definitely on our radar, and we apologize for the inconvenience.