Could you please share the arguments that the Arbitration Committee members used when making their decision?

Both Stinger and the others.

Well, I'll share my opinion. Initially, I was inclined to let the game continue as it was, but after some thought, I changed my mind and voted in favor of allowing the turn to be completed. And here's why:
1. The bug was specifically related to the HD update, not the HellLight mod, which Baratorch confirmed. An updated patch was immediately released.

4.100 RC8 -> 4.100 RC9 (01/25/2016)

[!] The < Sys.ReduceCpuUsage > tweak has been renamed to < Sys.CPU.ReduceUsage > and is disabled by default. (This means that the tweak will be disabled upon updating, which will eliminate lag in the interface on some PCs)

2. HellLight couldn't have known about this; he immediately contacted the judges upon discovering the issue.
3. HellLight isn't asking to change the turn in a way that would allow him to rethink or play it differently; he's asking to make the exact move he intended to make but didn't have time to complete. The stream shows that he was trying to position his hero in the correct spot, but he didn't have enough time to make the final click.
Based on all of this, I voted to allow him to make that final click.