Fact is, we don't really know the extent of it. Personally I feel the decision to push Ultimate to 5.55 was the risky decision that predominantly lead to the delay -- it's already risky to push it so late within an expansion cycle, as if something unforeseen were to happen (be it a massive design bug/flaw they need to fix/or being put on battle design teams for the last Savage tier/Bozja battle content/and 6.0 content that'd stretch the team thin like in StB > ShB; or a lead design getting sick etc...would all automatically delay the Ultimate to sometime in 6.0 since "on time" was 5.55). If a lead designer on the project became incapacitated in some way, be it family emergency/fell ill etc... that would just stall the project until that designer was back in commission.
Putting 100% of the blame for the content on Bozja Savage lacks the potential nuance and ignores previous criticism when they announced this Ultimate was aimed as late as 5.55 and not 5.3. There's still a likelihood that, say, they cut development of DR Savage but still couldn't meet the 5.55 deadline for the Ultimate due to unforeseen delays in the development that (we) aren't aware of and likely won't be aware of.
Be upset, be disappointed -- I know I was disappointed to hear the news, but this whole "cut DR savage to save Ultimate" bit isn't necessarily even accurate, and misses all the other nuances and challenges that come with Ultimate fight design and just the battle design team's hurdles with their timeline.
Personally I'd rather have both, but with the way the world is intermixed with things already having been delayed prior, I was expecting something to be delayed heavily -- Ultimate coming so late meant it couldn't be pushed back to a later ShB patch (ie.: say it was slated for 5.3 and then delayed until 5.5, we probably wouldn't be having this discussion in the first place).
Not to say DR Savage isn't without flaws (it *should* scale like BA did in order to generate content longevity, Castrum should give much better rewards so it's ran more often in the first place so people can unlock the content etc...) but it's not... bad content. It's a lot of fun, to be honest, and I really enjoy these more experimental raids that let you play around more with various in game actions/abilities that lend into replay-ability.
Honestly I wish we could have had both, but with the state of things, it became impossible and something had to give. Just the reality of it.
At least, Sage + Melee DPS in 6.0 should receive Ultimate Weapons, so there's that tiny silver lining.