That’s a very fair challenge and it certainly got me thinking! I’m not sure I can strictly justify my approach in a pure Laws way

. Although, interestingly, I’m also aiming to get to the ‘what will help you manage the situation best’ outcome. Because a strict law interpretation could be highly problematic. I’ll give two examples to illustrate, one more powerful than the other …
1) The altercation is in one of the penalty areas. In that case, unless the actions of the attacker were clearly worse than that of the defender, you’d be obliged in law to give the penalty - we punish the ‘more serious offence in terms of sanction, restart, physical severity or tactical impact’
2) The altercation is close to the halfway line. Giving a FK to either team in this situation would allow for a long ball into the opposition area and the potential for a goal within seconds of your chosen restart.
Overall, stopping play swiftly in these situations is often important in terms of player safety. Having stopped it, we are then looking for the fairest restart and (other things being equal) a DB restart is designed to simply restore the situation that existed prior to the interruption. It may well be more spirit than letter of the law .. but that’s also true of instead choosing to give the FK to the team that suits you best.