I find it shocking that someone thought it was a good idea to list a flat on airbnb that they're only renting themselves. Largely in England subletting is not allowed under the terms of rental agreements.
It's irrelevant really in terms of the petition, as the site is a mechanism for British citizens to bring their concerns to the attention of parliament. I assume you would have to go down a different avenue to lodge your objections.
Note that I agree with your sentiment, just that that is what the site is for!
No, because, as per the help page https://petition.parliament.uk/help, only British citizens/UK residents are eligible to vote. No point undermining a legitimate process with illegitimate entries.
To anyone nitpicking, unless the headline has been changed since submission, the author actually says they built it "by hand", rather than "from scratch".