That's what the “in real life” bit was about. In real life, even with big-but-certainly-not-infinite n, O(n log n) heap sort usually performs better than O(n²) bubble sort.

2³² may not technically be “infinity”, but if you're looking at O(1) vs. O(n), in the real world n=2³² is pretty likely to make itself noticeable, performance-wise, somehow.