I agree with most of what you're saying, & I've been saying that RDR vs Fluffy for the next title shot after Caio/Imavov is a good option as well & that I wouldn't have any problem seeing that play out. But having him fight Strickland would be pointless because Strickland is now in the same boat as the guys you mentioned in MVP, Cannonier, & Izzy. Strickland could be looked at as a gatekeeper.
But Fluffy is a prospect. Beating Dolidze & Allen isn't title shot worthy. Not just because of their name value but skill set alone.
Strickland just fought for the title and is ranked #2, so beating him means a lot more relative to rankings/the division then Izzy/MvP/Cannonier (even if skill level he might be the same). Rankings are just to manipulate perception anyways, but since Strickland has a high ranking and just fought for a title beating him would give Fluffy not only the "name" value but the ranking and perceptive value that he wouldn't get from beating Izzy/MvP/Cannonier.
Fluffy is beyond a prospect at this point - he's had a 11 fights in the UFC and is on a huge win streak. He hasn't had the chance to prove himself against an elite fighter yet, beating a gatekeeper is relatively the same thing. Brendan Allen could be considered a gatekeeper, but I guess since it's MW a lot of these guys that are fringe top-10 are borderline journeyman/gatekeepers. Bo Nickel is/was considered a prospect lol, that's a "prospect" a guy with just a few fights that hasn't fought anyone in the top 15 and no one knows too much about their ceiling.
The top of the division has been stagnant for so long that you've got Izzy on a 3-fight losing streak ranked #4 and a clearly heavily declined Rob Whittaker ranked #7. Let's just be logical with who is ahead of Fluffy in rankings and the match-ups already made:
DDP > fighting Chimaev
Strickland > unbooked
Imavov > fighting Caio
Chimaev > fighting DDP
Izzy > unbooked, needs a soft rebound fight against another striker like Strickland or MvP (even Whittaker 3)
RDR > recent split win over Whittaker, needs one more top win that is more clear cut
Caio > fighting Imavov
Whittaker > recent split loss to RDR, pretty declined and based on RDR/Chimaev fights shouldn't fight pressure grapplers
Cannonier > fighting MvP
5/9 are booked, 2 guys just recently got in a 5 round war, Izzy is there but shouldn't be fighting guys with Fluffy's style (and neither should Whittaker).
The best fights to make for Fluffy are clearly RDR or Strickland in terms of setting him up as the next contender. I'd rather see RDR for the style match-up but sometimes when there aren't a lot of contenders they don't like to waste 1 of 2 viable guys (to me no one but RDR or Fluffy are in realistic streaking contention after Caio/Imavov), so Strickland wouldn't be outside the realm of possibility and would be interesting to see from a stylistic clash.