Especially since they technically exploited a bug in my own code.
Yeah that's called an intrusion, hackers do that and it's illegal. If you accidentaly leave you house door unlocked is it your fault if someone trashes your house?
Report them, no damage was done and it's a relatively minor thing so I wouldn't expect grave consequences, but maybe this person will be more more responsible in the future.
As far as I know Mint and Fedora have the same choice of Desktop Environment more or less, I'm really curious to know what you refer to when you say "modeen interface"