It costs money to make a decision, and there is no time left to profit with. Each decision created can only increase the amount of money that voters earn. The smaller number of voters who do vote on these decisions will take all of the reward?
It is possible to make someone lose a little votecoins, but because the smoothing parameter alpha=0.1, they are bounded on how much they can lose in a single round.
probably there are still things I don't understand...
Very good. Also, Voters have two weeks to submit votes (in my example timeline), regardless of how many Decisions are added or mature in the previous period (Decisions can't mature before they are added).
So Voters probably would NOT lose any votecoins, and just answer all of these questions and take the extra fees. Most likely of all, it would never happen.
Voters would not collect Trading Fees for these Decisions, of course, but that really isn't relevant because the (attacking) Authors don't collect them either AND the attacking Authors had to pay Fee1, so the problem is worse for Authors while Fee1 > Value of the median Voter's Time. (Note that, although each Voter only gets a proportional fraction of Fee1, each Author loses all of Fee1, which is the true purpose of Fee1). As all Decisions must be easily-verifiable (or face the dreaded .5 contingency), this will likely be the case. Voters, as a committed group, have all the power, they can just .5 everything and screw the Authors (the only requirement is that they feel other Voters will act the same way). If someone really did something crazy like add 400 Decisions at the last minute, that weren't used to make Markets and that no one traded on, it would become possible for Voters to coordinate in this way.
Finally, even if they did NOT coordinate in this way, and answered as many Decisions as they could, but not all of them, the protocol would still resolve the Decisions as-correctly-as-possible and, what's more, (they way I designed it right now), Fee1 would automatically increase. I'm actually not crazy about that way of setting Fee1, however. Perhaps just allowing the Votecoins to vote, with a 75% majority or something required to change, would be the simplest and best. Branches should have a little text info idea going over the specialty / rules, and these might need to be changed, which implies a changing mechanism anyway.
I'm more than open to improvements, though. As I said in "Intelligent Decision Fees", Fee1 can probably take some smart improvements.