If Russians were trying to hack into the Organisation for the Prohibition of Chemical Weapons (OPCW), it would have been to find out the degree to which the OPCW has been bought by and is controlled by the neocons' owners, the US plutocracy. After all, the OPCW hadn't been and still isn't following legal processes in investigating alleged chemical attacks in Syria and elsewhere. The OPCW reports always come out supporting, at lease somewhat, unsubstantiated allegations leveled by the neocons.
Just exactly why weren't the Russians arrested? Well, that's easy. They'd have an opportunity to defend themselves. By not arresting them, the West can leave the allegation hanging there unsubstantiated.
Plus, by taking their equipment (imagine that: taking someone's stuff even though there was no arrest), the West can doctor the supposed evidence while the Russians can do nothing.
How many foreigners are there all over the world in cars and with computer equipment? Is that proof they're all spies?
Anyway, I think the records of the OPCW should be independently audited to see just exactly how bought off that organization is.