the use of the word professional in this context is careless use of the English language.
I always like to think I can deploy the English language reasonably well so while I'm not the OP on this thread I'm going to respectfully disagree with you on that one...
Professional is obviously primarily a noun, ie someone who is a 'professional' is someone who makes a living at a profession of some sort. In this context it is obviously incorrect to describe anyone who does not fit this description as a 'professional' and the word carries no positive or negative connotation; it is merely descriptive of someone's status.
However I would argue that it does also have a secondary use as an adjective or adverb that carries a positive connotation, ie one can say someone is "doing something in a professional manner" for example which usually means they are proficient to a high degree at something. To give another example my instructor might say to me "your radio manner sounds very professional"; that does not mean I am a professional radio operator it merely means I come across well on the radio.
Nothing is clear cut in language but I think most people would agree that the word "professional" carries a positive connotation when used in the above way...therefore logically unprofessional carries a bad one.
Apologies for this non-aviation post, whatever the adjective one uses to describe the crossing of an active DZ it is clearly poor airmanship.