I always thought the team presentation and team signing on were not the same thing - maybe they are.
Sorry, didn't really mean to suggest they were the same thing - my understanding is that the presentation is just the formal public announcement of the team line-up, with the assumption that all the official paperwork is done behind the scenes beforehand. In any case, yes, there does seem to have been an element of hangng Bardiani out to dry, while in BMC's case, the authorities have acted swiftly to minimise the impact on the team.
You can understand why they would do that to Bardiani, but it's interesting that BMC as a team does not seem to have been tainted by this in the public perception. But the more I think about it, the more I think it's really pretty scandalous. I can't imagine Sky would have got away with it so lightly if it had been one of their riders. And let's not forget that BMC have the Andy Rihs connection...
Never really considered Sanchez as an especially dirty rider, although he has been around long enough to be tainted by association with the Armstrong era, and Euskaltel-Euskadi were prone to the odd doping scandal (Mayo, Astarloza, Gonzalez...). I've just never liked him because of his egotism and his tiresome milking of the Olympics win. He does seem very popular in the peloton though.