On the one hand you can argue that the Democrats should participate to keep an eye on the GOP members and call them on the unadulterated bullshit that you know the proceedings will be.
But that presumes that Democrats inside the Beltway have spines and will stand up to the Republicans rather than merely roll over and try to appear collegial and bipartisan. Clarence Thomas hearings anyone?
I wish they had stayed away. Let the GOP single-handedly continue this farce. You can still hold daily briefings to "set the record straight". But now you have provided cover, a patina of legitimacy, to what at best can be called a charade.
If only the inside the Beltway Democrats would listen more to the rank and file Democrats around the country, they, and the country, would be better off.