M,
1. You wrote “Important note: there is a large in-between category not mentioned in this paragraph, namely those who do not observe – or even commit some sins – but without the malicious intent of heresy. Lashon Hara against someone in this middle category is forbidden.”
a. Why did you quotation marks?
b. Do you then admit that today’s non-observant are not in the above category as they lack malicious intent (BTW, l’havdil elf alfei hevdelim this concept also exists in secular law – it is called mens rea)?
2. Threads evolve. This also happens in the Gemara until someone says “????”.