Actually, that is false. The only change to the rules was to eliminate the straw poll. The straw poll had always been non-binding, but rule changes at the RNC would have required the results of the straw poll to be binding had they held it. So to keep the process the same as it had been, they simply eliminated the straw poll.
However, the idea that this change meant that all of the CO delegates would be unbound is false. The people who wanted to be selected as delegates had to file a statement of intent. On that statement of intent, it gave the delegate candidate the option to run as a bound delegate for a specific candidate, or run as an unbound delegate. If they indicated they were pledged to a specific candidate and were selected, they would be bound to that candidate on the first vote. If they ran as unbound and were selected, then they were free agents.
Here is what FrontLoadingHQ said about the process months in advance of the actual process:
"Colorado has been talked about as a state that will send an unbound delegation to the national convention. That would only be the case if all the delegate candidates who file intent to run forms opted to remain unaffiliated with any presidential campaign. If those delegate candidates pledge to a presidential candidate and are ultimately elected to one of the 34 delegate slots (not counting the party/automatic delegates), then they are functionally locked in with that candidate if that candidate is still in the race for the Republican nomination."
I've seen exactly that stated in two sources. One of the sources quote the CO GOP chairman saying exactly that. I can't link that source--it's some green website (literally, the background is all green). The other site is the Denver Post. So, if this is false, take it up with the Denver Post: Republicans still will hold precinct caucus meetings in early 2016 to begin the process of selecting delegates for the national convention but the 37 delegates are not pledged to any specific candidate.
Now, to quote you: "The people who wanted to be selected as delegates had to file a statement of intent. On that statement of intent, it gave the delegate candidate the option to run as a bound delegate for a specific candidate, or run as an unbound delegate."
That is highly problematic. The delegates are a sampling of registered voters. We know that there are Trump supporters in CO (even though they didn't vote), and that their support is probably within the range that we see in other states, 35-55%. Therefore, it is statistically impossible that not a single person filing as a delegate filled out a statement of intent to support Trump. So, what happened?