That actually makes sense with how the remake timelines/multiverses being so different from the originals. Cause when I played HGSS i was so confused on why Lapras was in place of Espeon, i didn't think it was Red from FRLG and not Yellow
Gen 2 wasn't actually planned to be the end of the series. The Rumour apparently came about from one of the devs saying that Gold and Silver would be it for themselves. Basically a mistranslation or interpretation.
Say this in one of DidYouKnowGaming vidoes, the thing about gen 2 being the end of pokemon is not true at all and the blame falls entirely on the translation. When gen 1 became like the best selling game at the time, they already knew they were gonna continue until pokemon died. So yeah, thats not one of the reasons why Red was in mt silver.
Back in the day, I used to do challenge runs in Black and White 2 with "Canonical" protagonist teams! I looked up every possible fixed encounter and gift Pokemon you could recieve in each set of games along with any possible anime adaptations, then pretended to be that protag in my run! A fun example being Brendan with Sceptile, Swellow, Castform, Armaldo, Sudowoodo and Metagross!
It´s always intresting to see this old characters recontextualized with modern mechanics like Pikachu with Volt Tackle, never get´s old! (Always loved this video).