I expected it, and it's in fact a big mistake on Hamiltons behalf
the rules are very clear
5.4 Cutting:
5.4.1 No intentionally cutting corners of track. Two wheels must
always remain on track at while negotiating turns (Curbs count as
track).
5.4.2 If you gain a position resulting from cutting allow the car you
passed to overtake you before continuing a full race pace.
5.4.3 If a cut is unintentional and you do not receive a black flag for it
from rFactor, and you do not gain position from it continue as if it did
not occur. If cut corners continue to happen and you make time up
from them they will be deemed intentional
5.8.5 Passing outside the track or on the apron is not allowed. A driver
gaining positions by such moves should let those who passed
immediately regain their position. A driver failing to due so will be
penalized.
Hamilton did not slow down, and kept going at full race pace, only slowed down just enough for Kimi to get by, and instantly took back that spot.. you can't do that if you're following the rules, because you can't be at full race pace... on that straight, if he were not at full race pace... there would have been more then the half of meter space between Hamiltons nose and Kimi's rear-end... there would have been car lenghts.
i'm not even sure he slowed down, Kimi just had more momentum because he was on the race line through the corner where Hamilton had cut...
in which case 5.4.3 rules it was intentional...
you have to agree, his line was very optimistic going into that corner, he would not have been so bold if that was Monaco, and there was Armco instead of a runout zone