Perhaps similar to the “Post Without Disclosing Your Name” checkbox, their could be a “Post Without Disclosing Your Company” checkbox. If unchecked, the company would show. Their could be a little instruction/admonishment, e.g. “Uncheck this box if commenting on your own company, company’s products.”
This might encourage more disclosure from newbies and those who should know better.
The two checkboxes would be independent of one another.
Also, in case a concern is the cluttering of posts with company names, the company name could be hidden and only shown as a mouse-over.
*Maybe even a stronger encouragement could be given when the poster is posting undisclosed but his company name is in the post or the title of the discussion ;)