Is it inappropriate for two boys (friends), aged 13 and 10, to share a bed in our hotel room?

I think it's appropriate. Reading your comments, I feel like you must have a very strange idea of what 10- and 13-year-olds get up to during a slumber party, which is essentially what this is. They're going to talk about farts and video games and people they hate at school. They're going to dare each other to stay up past midnight and both fall unconscious before 11. I get that you want to avoid heteronormativity. That's admirable. But in all likelihood, these boys are both straight. Which is not to say straight boys never experiment sexually with each other, but it's rather less likely, don't you think? Obviously, there's a small chance of sexual experimentation whenever your child is with another child and outside your supervision. Do you never allow your child to be with other children outside your supervision? If so, I think you have an unhealthy obsession with preventing your child from experimenting sexually. I understand that the thought of this makes you uncomfortable, but you don't get to set the schedule for your child's development. Also, I have to ask -- are you sure you're afraid of sexual experimentation? There's a significant developmental difference between most 10-year-olds and most 13-year-olds. Are you actually worried that your son will do something the younger boy doesn't want?

What are my thoughts? My first thought was, My goodness hasnt this person ever shared a bed with someone without wanting sex? Second thought was: They should ask the boys involved if they mind or not, that is really the only consideration necessary in this instance.

The question makes an assumption that is entirely unwarranted. It assumes that two young people sleeping in one large bed has opportunities for sexual experimentation, while two young people sleeping in separate beds in the same room does not have opportunities for sexual experimentation. That's incredibly unrealistic.  Furthermore, if, and at what age kids start to experiment sexually is not significantly impacted by whether or not parents "provide opportunities", attempting to eliminate "opportunities" will instead most likely backfire - the likely result from such attempts is that sexual experimentation happens anyway, but under more unsafe circumstances. I think it's pretty unlikely that kids in this age would get up to anything sexual anyway, and even less likely that this would happen with parents sleeping in the next room, so I think that you're choosing to limit entirely innocent behaviour based on a unfounded fear that something sexual "could" happen. May I ask at what age you would want to provide an area for sexual experimentation ? There's good reasons for being skeptical of children having their sexual debut very early, and good reasons for wanting people (of any age!) to have safe sex. But attempting to control sexuality by way of restricting access to "opportunities" is misguided, cannot possibly work, and is likely to instead lead to behaviour which makes sex more risky any not less. Examples of things teenagers do in response to parents who attempt to restrict their opportunities include not carrying condoms (for fear that parents would discover them) and having their sexual debuts on parties or in the back of cars under stress and nervousity -- rather than safe and with all the time in the world, with ample access to contraception and a minimum of shame about using them. (but 10 and 13 is early, these concerns are biggest around age 14-18)

I'd vote for separate beds or even a sleeping bag on the floor ... independent of whatever sexual fun you do or don't want your kids to have. It's just more respectful of each person's space. People at any age may thrash around at night. That's especially true for boys, where there's more of a territorial marking quality to it. Accidental kicks in an unfamiliar bed are annoying. Getting both kids to sleep will take longer if they're under the same covers. I won't even mention burping, farting and such.

The boys are not going to be messing with each other unless somebody has been messing around with one of them. You have got to nail down where this is coming from in you. Fear, intuition, stories, experience? Something. They are likely to play games until they're exhausted, then crash.