Second, uploading something to AUR4 then immediately orphaning it is stupid. Why not just hold onto it for a while and look for co-maintainers, or a new maintainer? By orphaning, you just became the "thinned" part of the herd.
Well, if it's orphaned another potential maintainer who comes across it, might be more likely to pick it up. If it's *not* orphaned, they'd have to contact you first to ask you to transfer ownership or add them as co-maintainer - and even though that's not a *big* social cost, it is one nonetheless, and some potential maintainers will just not bother. I.e. it's a matter of making things run more smoothly/conveniently. IMO orphaned packages should *only* be deleted after an ample grace period (for example, when they've been orphaned for at least 4 months or so).