Yeah. I know very little about radar but I am quite dubious of this method.
What I do know about OTHR is that it needs a very tightly-controlled set of conditions to work and I am doubtful that this is achieved with passive WSPR analysis, per the German author you linked to. The little bit that has been disclosed about his method(s) isn't that revolutionary in terms of signal analysis and if it were that good, then it would have been more widely in use already with much higher SNR signals.
Godfrey's follow up paper (which will not be as attention grabbing) better be chock full of proof of method validation results, hundreds of pages and many, many results from many, many different aircraft in a variety of conditions, etc., etc. 50/50 chance that he will claim that his algorithm, which relies on his simple little laptop post-processing a bunch of MATLAB files, is "proprietary" and he can't release it, which would have allowed others to validate his algorithm. Cold fusion, anyone?