likely scenario comment above - agreed!
Yes its quite likely, esp. knowing that the PC is owned by this actor! Framing him would be perfect given his Law & Order links.
I've been involved in a similar search on office Computers in one of our departments in the past.
We quickly learned that because people have 'handled' the PC (us, or the repairers in this case) who are not official and impartial investigators, eg. the police, then the evidence can become non-submissible easily.
His 'attorney' or whatever, simply has to show that the PC was handled beyond the owners control (clearly used by the technician and previous owners) before any official investigative contact, and could have been tampered with.
What lends more weight is how the techy ended up rooting around non-system folders when he should have stuck to \Windows or \Program Files or more realistically just the Control Panel and Administrative Tools or his own toolset.
I would also bet that a search of the techys personal PC would turn up the same child pics, Either he's taken a copy (The curiosity and being able to show the high profile pics to his mates, if he has any, for 'fun' would be too strong), or he originally planted them, either way he'd be just as guilty in this regard. I say call him in for investigation too!!
But in reality this (sometimes rightfuly) doesn't stop people getting put away - point in question - Gary Glitter, but he's proven himself a dirty scumbag paedo in other ways.
It'll be very interesting to see how this one unfolds.