Short answer is that 6 OL is fairly normal...9 DL is heavy but not unheard of.
Long answer is a lil more complex...
I am not concerned about the 6 OL....when was the last time you have seen a situation where you said "wish we had that 7th OLman." I bet the Riders have carried 7 OL in a game maybe a half dozen times over the past decade...you will see 7 on a 46, but not as much on a 44, so one is sitting. It is a pretty common thing around the league. You don't rotate the OL...chemistry is too key. Further, you have at least one DL who can can sub in on the OL, but very rarely can an OLman cross and be effective. In the Rider's case, first man up is Steele...who has actually started as an OG in the past a few times.
For the Riders specifically...Harrison can cover either OT spot if needed and then Bladek would move in as RG (this is why he was kept over Bond...because head to head at OG Bond won but is less versatile OT wise) and would not need to be a DI because he is already starting. If there was a second OT that went down LaBatte would move to one of them and Steele would play OG.
The theory with being heavy on the DL is always having fresh legs...which can be huge late in a close game. You are seeing teams dress 7-8 pretty commonly now actually. For example...Toronto has 9 DL tomorrow as well. I believe they have 2 less receivers and one more DB and one more OL...otherwise it looks pretty similar. In a pass heavy league where a big Rider strength is receivers...I don't mind keeping more of those weapons dressed.
next part is special teams...especially punt coverage. You want a few guys with size to block but who can also cover. OLman covering...nope. This is where being heavy on exterior DL and LBs comes into play.
Also on STs...long snapper specialist. Most of the time, this eats up a roster spot and they play nowhere else. a kicker doing all duties...we start to see why this can be so huge and why Wally likes it.
I would like to see an extra DB dress....but that likely comes at the sacrifice of a WR and right now Carter is the extra DB. At the moment Marshall was not the best newcomer DB in camp...hence me wishing they dressed another...but his potential is really high and he can play probably any position in the game including QB very well....he could legitimately be in the rotation, outside of OL/DL
Another point is Thigpen...
....expect to see 9 DL for 2 weeks and then probably 8. There are a few guys fighting it out for a spot. Hughes and Jefferson are locks. Antigha is likely as well and would need to play himself out of it. Striker can play LB well, thus has that ability to roll back in a Jones D...so he is probably ahead right now. honestly...he is listed as a DE but is more of a LB. none the less...he is in competition with Geter, who is more of a traditional DE, and Maggitt...who I suspect might get a start next week. so there are 3 or 4 of those guys around fighting for a spot.
...this is where Thigpen comes in. Seeing as he is suspended for 2 weeks, it gives the team a chance to let a couple guys fight it out for a roster spot.
...the wildcard is Reaves...who came in and had a strong camp and is a solid special teams player. Not sure what will happen there, but he provides a lot of ratio flexibility. They can bring him in and have all import LBs or move an import inside on the DL. If Judge and/or Teitz show well...Reaves job security decreases down the road and that would be one less DL as well.