Thats right, on running across the US section, there were no independent witnesses to his run.
At the time i used to read Garside's website and entries (no such thing as a blog then) and i was, and still do subscribe to the DRS - the dead runners society. Every day on his run across the states, members of the DRS offered to run with Garside whenever, he wanted - every day there was an excuse from Garside as to why he couldnt meet them - he took a different route due to flooding, land slip, road works etc - or he had set off early that day and they had missed him, a number of times they would drive his route, but they couldnt fine him - then he is suddenly in New York for the flight to Europe. I agree he may not have wanted to run with them, but if I or, i think anyone had done this feat, you would want to shout it from the rooftops and tell/see everyone - you would want to write a book about the adventure, get media coverage, get the rights to a film etc etc - but no, as the article says - he would not answer his phone, ignore his emails etc.
if you had the time and the inclination, the DRS archives are searchable, maybe the author of the article should have looked in there for research purposes.
yes, apparently guiness have recognised his achievement, but i cant find the entry anywhere in either the book or online versions.
also, it wasnt only Blakie who was questioning him its just that blakie had a very large ultrarunning website so had a bit of a louder voice. There were lots in the running community at the time, and the media who wanted more evidence from Garside
So i wish Garside all the luck in his round the world swim, no doubt he will make sure that it is well proven.
I remember reading about him at the time of his run. There were numerous runners in America who wanted to run with him as he passed through their area. Somehow, he managed to miss all these requests all the way across the US, they even asked him, on his website at the time, where he would be, so they could meet up. Then he finished his run across the US without meeting or seeing anyone not only in the US though, but other than the girl he met in Australia, no one else saw him(?) - quite an achievement in itself. So did he do it? well he had plenty of options to validate himself - but he always had a reason not to - at the least its a questionable record i think personally.