This is about ASL joining the AOA, not pay and conditions.
Here are some points to consider:
How many more ASL will come if the offer to joing the AOA, goes with the negotiated offer between the company and the AOA to join at the bottom of the seniority list?
The extra 1% would be nice in the AOA coffers and get everybody on side but how many in avaiation would love to have the benefit of hindsight?