If anyone had ever bothered to read how TIOBE arrives at it's BS index you would no that this ranking is just as meaningful as "The best SA websites" or "The best paid IT job". Even if TIOBE had used job-postings on job-portals, this would be no good indication. Especially in industrial and military applications you will find "exotic" languages such as C/C++, ADA, assembler etc. Ada for example was possibly the most robust language when it was introduced a good 30 years ago and included features which provided the robustness/stability needed for defense/military applications.
Not quite sure what Denel used, but we developed mostly in Ada for defense systems and some odd flavors such as Eiffel, Smalltalk. Point being, that just because TIOBE can not find "+COBOL programming" across a representative number of search engines, does not mean the language is dead. If you want to get paid >EUR800/hour you contract out as an Ada/assembler engineer to DoD.