I’m pretty sure that your rationalization for that move is off. You may be right that he is not a franchise left tackle, but I don’t think him testing positive is the reason.
On a sidenote, players and teams should go into full lockdown for the rest of the season. It worked last year, and it can work this year. It may be that the team that comes out of this with the fewest positive cases is the one that stands on the highest stage at the end of the year.