He's a successful 6th round pick. Most don't make a roster and get stuck on the practice squad. If you can get a backup from the 6th round, that's a win. And that was probably always his ceiling: Backup tackle.
Your right.

John Schneider traded back into the draft to get him. Forsythe did alright toward the end of the 2022 season at right tackle
The OP quoted tweet of observation was posted at 7:58 pm while the game was in progress. It was not, a post game player evaluation. Lineman look better after accumulating some game reps, after post game coaching and tend to thrive playing next to incumbent starters .... ect. More often than not, it takes a few weeks to sort out an offensive line.
So many forum posts are myopic. Can't see beyond a reactive emotion. Can't help but singled out someone to belittle. If not Forsythe, someone else would have been targeted. We'll see whose turn it is next week.