Maybe I am cold hearted, but I don’t feel any sympathy for their position. They were busy, so they should get out of the contract they willingly entered? These are educated adults that should have known better than to sign something without reading it.
Now the counter argument is that no one reads EULAs, but courts have held at common law that only abnormal clauses not in line with industry standards need to be highlighted to draw attention, or otherwise explicitly initialled. In this case based on at least one researcher asking if there were conference fees, it seems that there is at least some precedent for fees being charged to speakers (something that surprises me, but I guess it adds value to the speaker’s CV), so again, I have a really hard time feeling like this isn’t the result of a bunch of people not reading their contracts closely and treating their signature as something less valuable than it is - a binding commitment.