I don't understand that attitude. If you simply pushed the code to a github repo with a note that you won't be providing any support and disable the issues page, why would you feel any burden?
I did exactly that with a Heroku buildpack. They featured me in their official registry anyway. Shortly afterwards, I started receiving insults via my github commit email from people who were Heroku customers and furious that my (free + OSS + unsupported) buildpack didn't work like they wanted to. They paid for Heroku support and mistook my OSS for a Heroku product, so they felt like they are rightfully entitled to me providing support.
Half-kidding: sounds like a sales opportunity. "I'm not Heroku but I might be willing to help if you give me your company plus x". Only if the stars align in so far as the request is not insulting, you actually do happen to look for money and the requester would be willing to pay (never happens because even if "the company wanted" your contact would be in no position to decide) you'd name an adequate price. But yeah, those stars certainly won't align. The only benefit you can get from receiving those mails is a tiny glimpse into who might want to use what you made.