This is true. But even back then it should have been apparent that pandering to Tumblr would be a bad idea that would cost RWBY (and RT) more than they could hope to gain in the long run. I recall (that was the Gamergate 1.0 era) that even in 2015 or so, Tumblr was already known as a containment zone for deranged SJW types and especially out-there porn artists, and had even gotten into & lost a 'war' with 4chan. I guess Rooster Teeth fell to the same bug infecting much bigger companies and compelling them to keep pandering to the descendants of said Tumblrinas even after it became obvious that that was just turning off their actual fans & tanking their profits to a point where they've lost (and are still losing) way more money than RT had ever made.
I suspect another element to it was that RT themselves had always been liberal-leaning, so they were always more likely to pander to that crowd than not. They were, after all, urban techbros based in Austin (the main liberal hive of Texas) and tech/'nerd' culture in the 2000s-early 2010s was a pretty left-wing landscape compared to today when it's been gutted by said left (most self-described right-wingers in tech from that time period were libertarians rather than doctrinaire conservatives IIRC, Marty O'Donnell the Halo composer & audio director was one of the most notable exceptions). It's just that they radicalized in time as the rest of the mainstream left did after GG and the 2012-2016 elections, but building an echo chamber of (not-so-ex-)Tumblrinas for themselves couldn't have helped with that since it meant they were constantly bombarded with increasingly inane far-left fearmongering in addition to fan demands, and it really shows not just in RWBY but also their later Twitter posts. I am not aware of RT screaming about Mitt Romney being a fascist or publicly celebrating Obama's reelection on social media in 2012.
Notably Ruby's design used to have crosses to pin her cape, but those were ditched from Volume 4 onward. Guessing at Monty Oum's religious inclinations is even more difficult than guessing at whatever ultimate vision he may have had for RWBY, and I would be enormously surprised indeed if it turns out that he had been a zealous Christian in life. But I will say that being an American-born & raised animator, he must have been aware that there's a lot more to that symbol than 'wow it looks cool' unlike most Japanese anime artists who throw it in (especially in the '90s-2000s when he was growing up and would've been exposed to anime for the first time).
If I'm to guess based on the company he kept, Shane & Dillon seem totally apolitical and (very much unlike modern RT) have never tried to bring RL politics into Dillongoo Studios' work or social media AFAIK, so I think it's most likely that he was either also apolitical himself or a normie liberal type and consequently would be weirded out by the likes of the Bumblebee Tumblrinas had he lived, even before they started getting in his face about binning Black Sun and forcing BB through (almost certain to provoke a highly adverse reaction from him, given how fiercely he was willing to fight the rest of CRWBY over creative matters). I highly doubt he (and they) would have pandered to that mob had they been able to pull off his break with RT, the sort of person who would care to appeal to what Tumblr was already widely known to be like in 2014-15 would never have put crosses on their main heroine in the first place.