it has no (Ask Ubuntu) owner
It has an owner, its called Ask Ubuntu and Stack Exchange via the copyrights license that Stack Exchange uses. All the work you produce on the site is considered owned by public domain, not user defined.
Just because the user is not here anymore to reply to anything does not mean it should be deleted. In fact, according to the license a user cannot go ahead and start deleting his own content just because he thinks that's what should be done.
it's over a year old
So everything over a year needs to be removed from the site? Don't label things abandoned just because... It has answers and it contains valid information for anyone still looking for that information.
about 10.10 / an old boot-failure
That is no reason to delete things on the site. I think you are referring to it as that release its not supported anymore, so we should delete it.
That is just wrong, there might be people still using it even if its not supported anymore, ie: Windows XP mainstream support is long gone, but I still use it professionally and that requires me to look for information to solve issues from time to time. Thank Darwin that the internet doesn't go ahead and deletes random stuff just because its outdated and support has ended.
In the end, this should be a community decision. As Fossy-pants says there, you are almost 3k, if you want to vote on this to be closed you should try harder to get the privilege of doing so.
Meta is really not the place to take these things. Unless its urgent, sensible content, offensive in some way that deserves discussion, avoid creating a fuzz where there is not.
Get another 50 reputation, vote to close it, link it in the regulators and see if anyone else agrees with your reasons. That's what needs to be done here.