I'm not familiar with any of the listed currencies, but in a properly-designed cryptocurrency a deposit to a given public key is just any transaction[0] that includes a output to that public key. There's no such thing as accepting or not accepting deposits, at most they could actively refund them, which bankruptcy presumably prevents them from doing.
IOW, they're saying: "If you give us money, we will (/may) be forced to give it to our creditors rather than back to you, so don't do that.".
0: IE, a message published by Alice to the effect of "[Alice's public key] gives [Bob's public key] X [coin]s. [Alice's signature for this message]", published on the distributed ledger. Note that Alice can create and publish such a message without any input from Bob.
IOW, they're saying: "If you give us money, we will (/may) be forced to give it to our creditors rather than back to you, so don't do that.".
0: IE, a message published by Alice to the effect of "[Alice's public key] gives [Bob's public key] X [coin]s. [Alice's signature for this message]", published on the distributed ledger. Note that Alice can create and publish such a message without any input from Bob.