"This attempt was made in accordance with the regulations of the FAI Sporting Code including the provisions of 5.2.2.3 on Unsporting Behavior."

and googling for that reveals:

'5.2.2.3 reads: "Unsporting Behaviour. Cheating or unsporting behaviour, including deliberate attempts to deceive or mislead officials, wilful interference with other competitors, falsification of documents, use of forbidden equipment or prohibited drugs, violations of airspace, or repeated serious infringements of rules should, as a guide, result in disqualification from the sporting event."'

So I'd guess for official World Record attempts (and probably for the prize rules) doping is out. (Sounds like the pilot has enough other sporting pastimes that he'd be unlikely to dope just for this project too…)