It actually IS possible for the casino to rig the software. However, if it’s a nasty casino- a.k.a. ROGUE casino- this is not generally the way they will try to cheat you. There are simply too many people out there who will figure it out and report it. Of course, sometimes this is worth it for them because the online casino can simply close down after people figure it out, and the operator can run off with the player’s money. Due simply to the nature of conducting business on the Internet, there’s usually no way to find this operator or prosecute them.
By comparison, reputable casinos are audited on a monthly basis, licensed, and run only fully tested and certified software (with a certification that is completely up-to-date). This means that while you’re still likely to lose at them, you lose because of the House Edge, not because the casino is literally cheating you. 'Offline' roulette is still technically On Line- it just isn't live, so you can play at a faster rate if you like. At a secure, fair casino, both versions of roulette are safe. You know the odds going into it, and the casino does nothing to alter those odds.
Swiss Casino does not seem to be on any rogue lists, and when I looked up customer complaints about it, I found that most of the complaints were happily resolved. I think there are better places to play, but that’s just my personal opinion. As far as being ‘safe’ to play at, Swiss Casino appears to be legit.
In the future, you can learn to spot rogue casinos before ever playing at them, simply by doing a little homework before you sign up. Online Casino Slots recently did an article on it: http://onlinecasinoslots.ca/component/content/article/300-how-to-avoid-rogue-casinos
Online Casino Suite also did a 3 part piece on resolving disputes with an online casino, if you should ever have trouble with one: http://onlinecasinosuite.com/casino-blog/online-gambling-disputes-part-i-how-to-go-about-resolving-a-legitimate-dispute-with-an-online-casino/573/
Hope that answers your question. :)