Many exchanges have similar policies, either officially (such as Bittrex) or unofficially.
The reason for this usually comes down to time and security. Any exchange worth their salt will have security set up in a manner to prevent human access to private keys, and prevent unauthorized tx signing even through an automated system.
While cross chain recovery is sometimes technically possible, with an exchange's systems in the mix it will often require:
- Someone with a very high level of trust manually accessing private keys, or accessing a system that will sign arbitrary transactions. For most exchanges, this will only be one or two people, as anyone with this level of access could move any funds to any address, and effectively clean out the exchange.
- That person's time. Due to security set ups, this kind of process will often not be a 5 or 10 minute thing. Considering that the person performing this action is going to be of a fairly high level, any time they spend on the recovery is time taken away from regular business, and is costing the exchange.
Due to this, most exchanges impose minimums and other rules on coin recovery, since it makes no sense for them to sacrifice security and time over small amounts.