I think CY knows the reforms stand no chance of passing, but is just acting on orders from Beijing. Quite possibly the communist administrators have limited understanding of how to win votes in a parliament which is not run by rubber stamp. What limited understanding they do have probably comes from dealing with FC reps, DAB politicians and sub-sectors of the CE Election Committee. Democrats are a slightly different breed.
I might be wrong, but short of blackmail I don't see what leverage the government and Liaison office has over democrats. They are already excluded from government and vilified in the press. And the democratic party was harshly punished in the 2012 elections, after having compromised with the government over the 2010 reforms.
The NPC decision seems too restrictive for any meaningful last minute concessions and any appeal to public support will be counter balanced by future large scale protests and the 800k in the July Popvote who opted overwhelmingly for a veto.