The initial positive reaction to Sirius XM's better-than-expected Q1 earnings was short-lived, leading to a decline in share price. This suggests that while the earnings beat was positively received, other market factors or investor sentiments led to the reversal in share price. The high relevance score is due to the direct impact of the company's earnings report on its stock price, and the importance score reflects the significance of quarterly earnings reports in influencing investor sentiment and stock performance.