I’m also one who would think of this as a false good idea. I mean if you sit next to a stranger on that coach, get along really well and end up saying “you know what, my wife and I are allowed a guest in the lounge, if you don’t already have access, would you like to join us so we continue our chat inside?” Then why not, but to just pick random people for the sake of it is both not really in the spirit of the guesting rules, unfair (you might pick the worst of the lot and leave out more deserving people by any criterion!) and could make them feel really awkward (including them wondering what you “really” want).

Ps: psychologists would also tell us that in either case our choice would never be truly random but would, instead, betray our prejudices. In fact, there are hundreds of psych experiments based on asking participants to ‘randomly choose’ among the strangers proposed...