Dominion-wise, this has a nice point, that you need to adjust to your opponent, but... there really isn't any advice here as to how to do that. 'When you're ahead, consolidate.' Well, sort of. But mostly how? What do you mean by ahead? What do you mean by consolidate? You have to know what you mean by this in order to put your advice into any kind of good use. Because a lot of people will read this and think 'oh, I have more points than him right now, playing my BM deck, I need to absolutely buy green every step of the way so that I have a big lead before his engine roars into life'. Which is basically wrong - you want to build more in this situation, generally, as the money player, with a number of exceptions of course.
'When you're behind, take risks'. Well, again, what do you mean? What does behind mean? Does it mean points, deck quality, both? How do I know when I'm behind?
Finally, there's also some kind of inherent strength of the strategies. What do I mean? To use your example, if you extend it past 9 turns to like 40 turns (more like a typical game of dominion...), then there's going to be no circumstance where before, I dunno, turn 8 (I don't know when it is exactly, without calculating), you should play anything other than option A. Because it's just stronger. In Dominion terms, two strategies have to be very very close for you to take a different road just because of seat. Now, later in the game, you need to make different plays more often, because the situations change a lot more. But the idea that I should play some strategy other than the optimal one that player 1 just took, just because I'm player 2, is generally a losing proposition.
Finally finally (yeah, I know I said finally earlier...), the one really concrete thing. Double steward. It's generally a really bad opening, unless you have a $2 you really want to buy early on (lighthouse, hamlet, crossroads). In those cases, it can be pretty darn strong. Otherwise, in your best case scenario, all you're doing is trash 4 cards all reshuffle long, and buying nothing. Which is almost never better than, say, opening steward/silver (or some other 3 or 4 you want) and then picking up your second steward on the reshuffle.
Having said that, I think people are way too scared of things like terminal collision. Thing is, if you're going to have that bad luck, like the 20% of the time worst luck, you're probably going to lose on any strategy (if you're opponent is much good). So go for the risks anyway. Indeed, I think people don't take risks nearly enough, and this is true in the P1 or P2 seat.