I find it weird though that Bittrex doesn't allow funds to be recovered after their stated withdrawal time frame. It's clear that not everyone will be able to withdraw their funds on time.
There should be a policy in place that makes sure users who didn't manage to withdraw their funds will still be able to get them. They state assets become unrecoverable, but how exactly? Do they burn them or what?
I see nothing weird about it. The announcement first came in 1st September I believe (you can find articles from Cointelegraph and bitcoingold's official website as well) about delisting so It was obvious that everything will be removed afterward. It's a procedure that every exchange does.
Also, by that logic, an exchange should keep running servers/nodes and customer's data regarding BTG for ever? otherwise how else they could give users the BTG? I think making the announcement on the 1st of September, delisting on the 14th and totally removing the withdrawals in 5th November make perfect sense and is fair. We've said this a billion time, an exchange is not supposed to hold your funds for long term, It's for trading and nothing else.
As for the funds, It's clearly not burned, it becomes their priority and yes, they probably hold it or sell it elsewhere.
@OP, I don't like Bittrex since their KYC move where they forced everyone to do it and I'm no longer using them, but just because I don't like them doesn't mean I will be against them even when they're right. Sorry to say, but it was clearly your fault.