Interesting point! But is this proof of "at least two bio students grappled with the arguments and weren't convinced" (not surprising) or "two curious (but otherwise random) bio students grappled with the arguments and weren't convinced" (surprising, should lead to a downward revision)?
I'm not sure they would be allowed to reach a pro-cryonics position. The acknowledgments say "Finally, we would like to thank our opponent group for their pertinent and helpful comments on our work."
EDIT: OK, apparently not.
Luke Parrish points me to what is clearly by far the most serious critique of cryonics ever written: a 57-page treatment by Evelina Martinenaite and Juliette Tavenier, presented as a 3rd semester project at Roskilde University in Denmark supervised by Ole Andersen.
Full paper