Here's why:
* Grave consequences and dire urgency convey a sense of seriousness and importance.
* Cautious and timid suggest hesitation and a lack of confidence, which doesn't fit the sentence's strong language.
* Aloof implies detachment and indifference, which is also not reflected in the sentence.
The sentence's tone is better described as:
* Urgent
* Serious
* Grave
* Concerned
* Alarmist (depending on the specific issue)
The sentence is clearly trying to emphasize the weight and importance of the issue at hand.