Well spotted!
Yes good question .
Maybe the witness cannot be sure on the day especially if he she does that journey every day .
If it was CL then the witness got the height of the left handed smoker ( and Claudia’s) wrong because we know Claudia was 5’ 6” herself.
It’s probably not easy judging the height of someone standing still while you are riding a bike.
If it was Claudia (and I believe, it was her), it doesn't matter much, whether Wednesday or Thursday: in any case it could have been the perp, who made her disappear.
I have questions:
Why did he have to intercept her on the way to work, in the morning before 6am, in darkness?
Why was it so urgent to speak to her in the early morning?
Why did they both stand still, why didn't he accompany Claudia on her way, because she had to be at Uni in time?
Why didn't he talk to her over the phone instead of meeting her?
Why didn't he visit her home (if he didn't)?
Who shouldn't know (if so), that the two were communicating or meeting?
Why was there no parking car? Did he come on foot?
It looks like he confronted her, when Claudia had to walk there at that certain time.
It can't have been a friendly talk. First a jealous, married (or in relationship) man comes to mind, whose calls she didn't answer and who had fears of being seen with her. IMO - It doesn't help, as always.