Yes you can report any incident, the rules for rejoins are
here. The rejoin rule specifically addresses whether or not contact was made.
The penalties can involve a loss of places, they do not account for following drivers. I don't see anything dirty in the penalty system but it is always open to discussion.
I agree not every incident is clear cut, if it was you wouldn't need a moderator to review it, but the rules are there to show drivers what is acceptable and what can be expected in certain situations. The penalties are clear.
It's not appropriate to discuss this incident specifically but, as per the moderation, the rule says
'The rejoining driver was NOT in full control but nevertheless attempted to drive straight back onto the racing line without any consideration for other drivers and contact was made, 2 places lost'. If you feel the rule is unfair it's open to discussion via the season review.