I'm sure that someone like apirchik will come along and be able to do this more justice than I am able to do it.

Lot's of Israelis go to Sinai to relax, get stoned, chill. Probably thousands at any given time. They don't ride around in tourist buses. If amongst themselves they can avoid speaking Hebrew they likely will do so. So a bunch of people who are taking a long weekend in Sinai and happen to be Russian Israelis would speak Russian amongst themselves. In fact they don't need to be in Sinai to do so. Workplace coffee room, work conversation on the telephone, etc. This has nothing to do also with whether or not they are Jewish. It is just natural in the same way that I speak English with Dovster when I see him once in 4 years.