but then we and our simulated utopias would most likely be obliterated by the very first aliens that come across us
I doubt you'd have to wait for aliens - humans, trans-humans or AIs who stayed outside the simulation would likely do the job first. One reason I'd have no desire to enter a simulation.
Natural selection deals with most wireheads. However, there are scenarios where the entire civilisation does this sort of thing.
If there are no competitors in the short term then natural selection's action could be delayed - until some turn up.
The question that the ideas are supposed to be in response to is:
Here are links to some proposed ideas that you should vote for, assuming you agree with them. You do have to register to vote, but the email confirmation arrives right away and it shouldn't take much more than two minutes of your time altogether. Why should you do this? The top voted ideas from this request for ideas will be seen by some of the top policy recommendation makers in the USA. They probably won't do anything like immediately convene a presidential panel on AGI, but we are letting them know that these things are really important.
Research the primary cause of degenerative diseases: aging / biological senescence
Explore proposals for sustaining the economy despite ubiquitous automation
Establish a Permanent Panel or Program to Address Global Catastrophic Risks, Including AGI
Does anyone have any other ideas? Feel free to submit them directly to ideascale, but it may be a better idea to first post them in the comments of this post for discussion.