He is not a player; he is an invited judge. And he monitors compliance with the rules. The rules in the ongoing tournament cannot be changed now (as they could have affected the outcome of games that have already taken place).

It's not up to you to decide what can and cannot happen. If the tournament is played according to certain "old" rules, then these "old" rules must be written down somewhere. In this case, it says:

1. By default, games are played according to /topic/10593/

The tournament regulations state a link to the rules, and therefore if the content of the link changes, the tournament rules also change.
Regarding red rush for Heroes of Might and Magic, it says:
Clarification:

Red rush is allowed.

What should I refer to if such a situation arises in the game? To the link to the rules or to what was said before? Let's assume everyone understands and agrees about RR.

Regarding the timer rules, it says:

the time limit per turn is 8 minutes, with a chess clock - (21:00+08:00+01:15).

Based on the rules, it is not clear which timer takes precedence. The organizer must specify the timer in the tournament topic. Therefore, how to interpret the rules if both players stick to their principles is unclear.

I think that the organizer should format the regulation post more carefully so that there are no such precedents.