Yes that's true. We all test the bot here online. Because you need to have a connection to launch steam.
Yes a café release of steam exists but it isn't free. This one require no connection. You have to contact the valve team somewhere on steam web site.

But look at the forums there. There will be steam release to play offline. You'll just need to have an up to date version. But the date of the release isn't know yet... soon maybe... but you know Valve... (look at hl2 !! )
I think this offline version exist but isn't released (why?). I saw in these forums that an official cs tounament used an offline steam.

W8 & C