You are absolutely wrong. 75% of super computers run on Linux. Go and see.
The official list of Top 500 (last updated 2012/06) states "Sequoia - BlueGene/Q, Power BQC 16C 1.60 GHz, Custom" as the number one super computer. Sequoia is nearly as powerful as Titan.
The free and open source software world becomes more business oriented. This among other facts implies 1) more businesses/companies involvement; 2) adoption of permissive licenses (e.g. MIT License, Apache License) and hence integration of free software with proprietary counterparts; and 3) loosely-woven P2P software engineering practices. While the hobbyist and enthusiast culture of development will continue to exist, it is going to be controlled by companies and organizations.
You can send them a warning email (anonymously if you prefer so) telling them you would announce the flaw publicly unless they fix urgently. Give them a decent deadline as well.