If they buy there is no payments to send out, if someone else buys they send payments to someone.
But isn't this part of the major gripe here, is that the payouts are low after the fees? With a virtual miner they can literally pay you anything (within reason) they see fit. Oh... BTC/USD had a bad day... your multihashlet is now in the red... here's a satoshi to keep you warm and fuzzy... always profitable!
They don't have to have an inventory to keep on hand, so buying back doesn't do a thing for them.
I get your argument... but it doesn't make sense in the virtual miner world.
It goes something like this:
Option 1 (no buyback):
step 1: Sell hashlets for ~$10/mh
step 2: Payout "mining" earnings - ~$6/mh over the miners lifetime (just a guess)
GAWs Profit = $4/mh
Option 2 (buyback):
step 1: Sell hashlets for $10/mh
step 2: Payout earnings until the miner is sold back to GAW - maybe $1/mh.
step 3: Buyback hashlet for pennies on the dollar due to misleading sell form - (GAW might buy 50 mh/s for $5 or ~$0.1/mh)
GAWs profit = $8.9/mh
GAW has an incentive to buyback any shares that are being sold for less than the expected lifetime earnings.
Even though hashlet payouts are piss poor, the lifetime earnings are still an order of magnitude higher than the $/mh some people are accidentally selling their miners for.