I believe this is one strategy among many others that e.DIGITAL trying to prevail in inter parte review . But all depends to interpretation of PTAB judges.JMO

The Bottom Line

"In conclusion, the evidence submitted in a PTAB trial must be carefully selected and tailored for the audience to which it is intended: PTAB judges who are very experienced in patent law and who are highly technically trained. PTAB judges are usually able to read the patents and printed publications relied on by the parties and reach an opinion as to patentability without heavy reliance on expert testimony. It is essential that any filed expert declaration is persuasive and tells a story that is consistent with the weight of other documentation published before the relevant date. Further, challenges to the analysis and conclusions of an expert are best made to the weight the expert’s opinions should be accorded as opposed to a motion to exclude the expert declaration on Daubert grounds. The PTAB is more likely to accord questionable evidence no weight as opposed to excluding the evidence from the record."