As I said in the article, these are my rules, and I don't
enforce them on anyone (I don't work with people who need
other peoples guidelines - and usually I don't work with anyone).
It's my code that needs to adhere to the given guidelines.
Furthermore, I was using SHOULD and MUST in the same sence
RFCs use them (that's why they are capitalized). MUST means
MUST. It doesn't mean "most of the time, but there are exceptions".
That's what SHOULD means. MUST means the rule should be followed
always. SHOULD means the rule should be followed usually, but
there might be exceptions.
You don't want to discuss tabs, but I'm interested why your
preference for tabs. What do tabs give you that spaces don't