How was it ever overcrowded from Colin's perspective, though? His brother Aaron pops out in front straight away as Colin follows. There is a bubble around Colin with nobody ever fighting him for position. Overcrowding was truly never a factor for Colin the entire race.
Your splits for Colin are off, as is your math because he was nowhere close to being four seconds faster than goal pace his first 100.
Let me help you all with the math and actual splits and then tell me if you really think pacing was a problem here. Apologies for the formatting of the "spreadsheet" below, but LR is run by absolute dinosaurs ffs.
(Colin's last 400m split) - Colin's actual split - 8:25 even pacing - 8:35 even pacing
100: 14.3 - 15.8 - 16.1
200: 29.6 - 31.6 - 32.2
400: (61.5) 61.5 - 63.1 - 64.4
800: (67.4) 2:08.9 - 2:06.3 - 2:08.8
1200: (64.9) 3:13.8 - 3:09.4 - 3:13.1
1600: (64.5) 4:18.3 - 4:12.5 - 4:17.5
2000: (66.3) 5:24.6 - 5:15.6 - 5:21.9
2400: (67.0) 6:31.6 - 6:18.8 - 6:26.3
2800: (64.4) 7:36.0 - 7:21.9 - 7:30.6
3200: (59.0) 8:35.0 - 8:25.0 - 8:35.0
Pacing was totally reasonable and over-crowding was a non-factor.