I want to be crystal clear: Sen. Durbin and the rest of the Senate Leadership will be aggressively whipping FOR the public option if it is included in the reconciliation bill the House sends over. Conversely, the Leaders will whip against any attempt to alter or amend the bill if the public option is not in it (or as your email says - whip against adding the public option as an amendment in the Senate.)
The reason is simple. There can be no amendments - good or bad - to the reconciliation bill once the House passes it and sends it to the Senate. The House will not do step one (passing the Senate healthcare bill in the first place) if they do not have assurances that the fixes they want (i.e., the fixes in their reconciliation bill) will be passed unchanged by the Senate.
This excuse is pure nonsense because the House simply can never get assurances that the reconciliation bill that they pass will pass the Senate unchanged. It is almost guaranteed that it will need to go back to the House for one final vote.
It is basically impossible to create a Byrd-rule-proof reconciliation bill. No matter how hard you work on it, there will almost always be one small provision on which Republicans could call a legitimate Byrd rule point of order. That would cause the provision to be removed unless it gets 60 votes to waive the Byrd rule. Since all 41 Republicans said they will never vote to waive a Byrd rule, that means any small offending provision could be removed. That would slightly change the bill, and force it to return to the House to be voted on again so that both chambers pass the exact same bill.
The only way you could assure the House that the reconciliation bill would pass the Senate unchanged is if Vice President Joe Biden declares that he is prepared to play real hardball, using his power as President of the Senate to ignore the parliamentarian's decision and reject all Byrd rule points of order, legitimate or not.
Of course, if Joe Biden is prepared to do that, effectively nullify the Byrd rule, there is zero reason the House Democrats need to vote for the politically toxic Senate bill as is. They could pass a “new,” merged comprehensive health care reform bill that deals with all the House's problems using reconciliation, with Biden nullifying the Byrd rule, so it can pass the Senate unchanged with only a simple majority.
Until I hear Biden declare he is prepared to play real hardball with the reconciliation rules, the excuse from Durbin's office stinks to high heaven.