The intent is to get rid of crawlers which are disrupting the operation of your servers. That’s not intent of doing harm to the crawler’s operator, or their business. It’s analogous to telling a hawker to fuck off: Polite, no, but them being able to profit off you is not your responsibly, you do not have to accede to that. And intent to harm the ISP is even less reasonable to assume.
cant find the primary source anymore https://netzpolitik.org/2012/berec-studie-dpi-bei-vielen-providern-bereits-im-einsatz/
That’s out of date anyway. How about this one. DPI is limited to OSI level 5 and only allowed to resolve network issues – and a crawler crashing is not a network issue.
Nah it’s definitely disrupting data processing, even though at a very low-key level – you’re not causing any data to become invalid or such. It’s the intent to harm the operator that’s the linchpin: “Jemandem einen Nachteil zufügen”. “Jemand” needs to be a person, natural or legal. And by stopping a crawler you don’t want to inflict a disadvantage on the operator you want to, at most, stop them from gaining an advantage. “Inflict disadvantage” and “prevent advantage” are two different things.
Good idea, but as already said before: First, you should contact a sysadmin. Who will tell you it’s a stupid idea.