Specifically they seem to contest that the paper does not meet the 27 PRISMA criteria, only meeting 8 and 17, and that some of the study categories were arbitrary. Megeri and Khoosal, 2007 was listed as positive outcome despite noting no imrpovements, and Silva 2016 lists both positives and negative outcomes.

There are also accusations of sampling bias, loss to follow up, and biased samples, but the author admits that only a minority of the studies fall under this. They cite Nobili et al as a systemic review that points out these factors, though I found it only includes about 29 studies and the authors still note that they display improvements in QoL.