According to the rules of racing:
4.15 Fouls: A leading horse, when clear, is entitled to any part of the track. If a leading horse or any other horse in a race swerves or is ridden to either side so as to interfere with or intimidate or impede any other horse or Jockey, it is a foul. If a Jockey strikes another horse or Jockey, it is a foul. If, in the opinion of the Stewards, a foul alters the finish of a race, any offending horse may be disqualified by the Stewards.
Clearly a foul was committed. Luckily the bumped jockey kept his cool or a terrible tragedy could have ensued.
"Section 12. Fouls. A leading horse if clear is entitled to any part of the track. If a leading horse or any other horse in a race swerves or is ridden to either side so as to interfere with, intimidate, or impede any other horse or jockey, or to cause the same result, this action shall be deemed a foul. If a jockey strikes another horse or jockey, it is a foul. If in the opinion of the stewards a foul alters the finish of a race, an offending horse may be disqualified by the stewards."
The latter sentence is the issue here. The only consistency Kentucky stewards have shown is to consistently ignore this rule, where no-calls prevailed for literally a century, dismissing even their own inquiries, not to mention jockey's objections and trainer's objections.
And on the rare occasions they enforced the rule, they only did so when the foul cost a runner a placing in the money; and even then, DQs have occurred almost exclusively between the first two finishers, with the winner demoted to 2nd.
Furthermore, the Kentucky stewards -- until yesterday - have been strident in interpreting this rule to avoid 'unjust enrichment', which would be for example, moving up Country House -- who was not impeded in the slightest, nor was a threat to overtake the winner.
Rather, as I stated earlier, this mistake was caused because Libtards believe in optics, and mistakenly believed that the PETA-induced hysteria at Santa Anita somehow would have caused a 'no-call' in this instance to be scrutinized.
Note, if you can, that the Stewards themselves didn't even light the inquiry sign. It was Flavien Prat -- a notorious 'herder' his own self -- taking a parting shot at losing with a jockey's objection on a horse who wasn't even fouled.