That may be so. This Syria thing has been handled so badly that it's hard to find any of it that has been handled well. But I'm not so sure I agree on this particular judgment. Or to put it a different way: diplomacy means always being remaining flexible enough to back out of brown bags you've walked into and grab other opportunities that may arise.
Why not grab on to this?
I'm not saying I think it will be easy or that the Russians are sincere. But getting all the regimes chemical weapons arsenal under international control would be no small achievement. Simply focusing on it would give the US something to apply leverage against (something it sorely lacks at the moment) and put the Russians in an awkward spot. The introduction of foreign forces of whatever sort is always something a regime trying to remain in power seeks to avoid. It would be a development that might well be used to leverage Assad out of power.
The key is that this potentially allows the US to reshuffle the deck and come at the problem on terrain which is inherently more favorable, given the Russian opening. Take the whole thing back to the Security Council. Have the Russians veto what they just proposed.
One might say this only amounts to a delaying tactic to stall US military action. But really? At the moment our tally shows that 232 members of the House are on the record as planning to vote 'no' - in other words, well over a majority. 47 are yes and 153 undecided. (If Obama can just get 150% of the undecided to go his way he's golden.) So it's not clear to me that there is anything to delay.
Is it ideal? No. But our current position is far from ideal. We should see this as an opportunity.