Yeah, a quick read of the relevant regs tells me Fanduel is gonna lose this one (Unless i've missed something)[1,2]
The law on this is pretty clear, and they can't unilaterally decide not to apply the gaming regulations of the state, or change them through their contracts.
(They can decide not to do business in states they don't like the regulations of course)
BTW, somewhat hilariously, the part they "..."'d is just 4 words.
[1] http://state.nj.us/lps/ge/docs/Regulations/CHAPTER69N.pdf
[2] (c) Upon accepting a wager pursuant to this chapter, a wagering cashier shall cause
the wagering system to generate a wagering ticket.
(IE them generating the ticket is acceptance)
(d) A wagering operator shall not unilaterally rescind any wager pursuant to this
chapter without the prior written approval of the Division.
(h) Winning wagering tickets shall be redeemed by a wagering cashier after
verifying the validity of the wagering ticket through the wagering system.
(IE they should have redeemed it because it was valid)
(k) No wagering ticket shall be voided after the start of the wagering event on which a wager has been placed
Another reason the could not have voided it.
Essentially the best argument they have is that it's a house rule under 13:69N2-2 .
This only works if their internal controls were approved by the division.
Even then, a reasonable court would likely find that clearly contrary to the written regulations (and thus, not a reasonable interpretation of the regulations by the commission).