That kind of thing is explicitly required under HN rules - if a company requires payment, it's only OK to post if a “workaround” to avoid paying is available.
Additionally, HN explicitly say it's OK:
* For HN comments to ask how to get around payment requirements, and
* For HN users to help other users to get around payment requirements
Source: Official HN FAQ page
On reflection, it's a great convenience to leave your cart around. So I think cart pushing is a valuable service to provide, and leaving your cart should be fine if it's stable and not in the way of anything.
If you don't, don't.
It's that simple. Be an adult, make a choice and live with it.
ETA: I dispute the implication that "honest" software is a category that necessarily excludes all ad-supported software, but that's a side story.