DOS means Date of Signing. If this TA passed, that would be this summer. The way it's written, anyone hired after two years from that date would start at lower pay. You would be unaffected.
That being said, I still strongly encourage you to explore other regionals. As I pointed out in the first post, you will still be starting at the bottom of regional pay even if this thing passes. If it doesn't, $22/hour. Why put yourself through it? And this needs to be said: I've flown with countless new hires who came based on things Marcin told them that weren't true and never came true. If you're coming for the same reason, research and consider this decision very carefully.