Pretty sure the O Line would also attend training camp and play in pre season games. These are professional players. Each person has a job to do and they need to do theirs. Not sure why the only allowed expectation is that Tua automatically loses a bunch of games. He ran a pro offense for a former NFL HC against a murderers row defense each week in the toughest conference in college football and thrived at it. Now he's just going to show up as some empty brain idiot?
That seems a little extreme. Here is what fans know, unarguably, from last year - Flo wants to win. He's not going to lose games just because the vet (RF) 'deserves' to start. I've said elsewhere, if TT shows he's clearly/significantly better (increases winning chances), he'll start.
But there's more to the equation than that. Physical talent is only one part. RF has the confidence of the team based on the last 9 games of '19. That count for a lot. If the competition is close, the vet wins. That's reality. How much will the OL factor into the decision? My inclination is, if it looks like game 2 of '19, RF starts. If it looks better than any game of '19, maybe not. we can debate how close TT's competition was to NFl through this decade. We all know rookie QBs make mistakes and, remember, Flo is all about winning.
Based on the above (and others I didn't mention), I expect RF to start unless TT shows he's clearly/significantly better (increases winning chances). The question then becomes when will TT start? A lot depends on how RF is playing and how the OL is doing. I'll not pretend to know that.