Isn't it also possible that Ron Conway and David Lee decided David should go because they didn't know what was going to go down, and then once they knew, Ron decided to distance himself from that group?
However, we know that two such dinners took place, and that David Lee was present at both. Also if they didn't know what was going to go down, why didn't David Lee want to go in the first place?
Again, we are only talking probabilities here, there is a huge amount we certainly don't know.
It's possible that Ron Conway intended to blow it up from the beginning, including his own plant there. But as it always happens the shrapnel takes the unexpected course. Consider this a badly botched operation.
I think the simplest explanation is that Conway either wasn't aware of the agenda or wasn't aware of the scope of it. That would explain his regret for Lee being there.