Can you please specify if low hashrate or a known vulnerability was the problem (or both)? With vulnerability are you merely refering to a more conservative max_reorg figure or do you think there is a more serious problem? If so, why can this be shared with the community or the devs when a problem in code is actualy found?
Space Blockexplorer is and has always been here:
http://space.midnightminer.net/ , working fine as I can judge from daily use.
SJW Blockexplorer is since roughly a year here:
https://sjw.netcraft.ch/ (this has been brought to Cryptopias attention even, also working fine)
GEN was unlisted because it's self-proclaimed dev Hort had an argument with Adam and it got delisted/deactivated same day (only quote of Horts post available:
https://bitcointalk.org/index.php?topic=1205536.msg16038573#msg16038573)
Also I asked Lafu about Space removal in a german thread and only got referred to their coin listing policy in general. leaving unanswered if there is a problem in code they are unable to share info about or just the low hashrate that they saw as a danger for double spends in deposits.
It is actually in the coin listing requirements that Coin devs contact Cryptopia as soon as THEY know there is a vulnerability with their listed coin. It is not Cryptopias job to chase up Coin devs even though they do, All coin devs agree to these requirements along with other conditions when their coin applies for listing and is accepted.