I think when it comes to consent, we usually do assume that someone’s not okay with something (or err on the side of caution that they might not be) rather than assume it’s okay to do something to a person unless they’ve explicitly requested that it not happen. It works the other way round, where we only do something to them if they’ve said it’s okay. Of course there are exceptions to this, such as helping someone when they can’t help themselves if it’s extremely critical or if it doesn’t violate them at all (like putting a warm garment over someone who’s fallen asleep in the cold), or what might be argued as necessary to do for a child’s development so that they can live a functional/healthy life. And then there are cases where it’d be ideal if we could not do anything, but the situation forces us to choose an option of what to do, such as dealing with someone’s dead body. In those cases I think the safest thing to do would be to choose one of the most common methods of interment, since 1. The person was likely aware (though not necessarily) of the main methods of disposing of someone’s body that are usually practiced by humans when someone dies, and probably had the opportunity during their life to object to them and request something different if they didn’t like it. 2. Those methods are generally regarded as the most respectful options available, and so statistically someone would be likely to also agree with that sentiment. 3. They’re also arguably some of the least invasive/violent/brutal ways of dealing with someone’s body, though of course none of them are completely nice since you’re disposing of a dead body after all.