Pre-order ASIC miner manufactures that keep customers hardware and mine with it for more than quality control purposes are committing theft of equipment used in the minting of money. One could argue that perfect counterfeit bills exist in circulation and that Bitcoins mined with this hardware can be considered counterfeit if not endorsed in virtue by the principle.
if its on the blockchain then their real. the blockchain itself is the endorser.
much like bank notes. if a bank says they are fake and wont accept them.. then they are counterfeit. but if they were produced 100% using the same protocols of a mint (paper/ink/security features) and it passes the banks tests to acceptability. they obviously they enter circulation.
the only bitcoin 'counterfeit' that could happen is in a totally different scenario..
and here it is:
someone says they will sell you bitcons but you have to download a specific wallet. and they will send you 1 coin for the $400 pricetag of bitcoin. you later learn that the wallet is not connected to the bitcoin blockchain, but a crappy altcoin chain. thus what you hold is not a real bitcoin even if the wallet shows all the bitcoin symbols and splash screens and everything else to make you believe the GUI was initially bitcoin.
what you are talking about in the OP is not counterfeiting, its fraud/theft. much like having a promise to a bank that the funds you put into it will be given to you in 2 weeks and the bank making 3x the money out of your investment and then making you wait 6 months and not compensate you, even though they have made all the profit they made by holding onto your investment.
morally in that situation, any profit/production you personally could have made in the 5 months 2 week delay you should receive. but if they say two weeks delivery and they deliver on time. then and profit they have made they 'could' keep.
all in all BFL are scumbags and should not only refund everyone. but also give them an average compensation of the extra coins they produced during the delay period.
the tough part is proving how long they mined the rigs for before shipping them. if you can prove that, then you can prove:
intentional delay
breach of contract (within their control)
which you can sue them for.