There is no downside, for it is potentially positive for any team’s third quarterback who is on a practice roster.
How I wish the rules as concern the emergency third quarterback in the NFL were simple, but they are not.
The goal of these complicated rules is to ultimately avoid the mess at hand in the playoff game of the 49ers at Eagles when both quarterbacks of the 49ers got hurt in the playoff game and a running back ended up playing quarterback for what was a bad look for the NFC Championship.
In short, the situation is more likely to be at hand late in the season should the team’s two quarterbacks be hurt, for teams are more likely have an emergency third quarterback on the game day roster just in case for those games.
This twist in the rule for quarterbacks on practice rosters probably won’t apply very much though, but teams are wise to keep a promising third quarterback on the 53-man roster but not activate him if they want to keep him unless of course they need him just in case to backup the other two.
The advantage here is that when the third quarterback is not on the practice roster, he can’t be poached and then perhaps later activated for play by another team.
The general manager and staff of all teams track all the quarterbacks all season long, much like players at all positions, of course.