He never even claimed this. He said they had a "personal relationship." Nowhere did he say they previously had a sexual relationship. And even for the sake of argument, being okay with messing around in the past does not imply consent to mess around in the future.
Regarding the photo, his statement said:
If she suggested what she MAY look like without clothes, that implies that this photo was clothed. What does "provocative" mean? Why did she send it (if true)? We don't know this yet, this will be interesting.
If he never got the opportunity to provide evidence during the investigation, yes that would be a sham. But according to MSU's statement, the parties had a chance to review the investigative report in July (which is a typical part of the Title IX process). So if he actually did have a chance to review, he also would have had a chance to respond.