It could be ideological, or it could be a common mistake people with a business background make in the government.
For the average for-profit company, the actual business the company does has no value beyond its ability to generate profits. The damage a disruption causes today can always be offset with higher expected profits in the future.
But for many government departments, the day-to-day business is the entire point. Any disruption can easily cause irrevocable damage. Even when the net outcome is positive, the gains often cannot offset the damage, because they go to different people.
I'm going to guess that the rationale is a combination of:
1) state's rights
2) anti-science
3) a number of people in the administration (very possibly including Trump himself) thinking that the CDC is an example of "the deep state" that conspired to keep him from winning in 2020
But, hey, Joe made groceries more expensive and the administration didn't kiss enough rear on the left side of the Dems to get Kamala elected, so, here we are.
Since losing in 2020 the various think tanks and groups that make up the right-wing have settled on a unified, frightening, vision of what the US government should look like equipped with (extremely dubious) legal rhetoric and reason to back it up. Most notable of these is Project 2025 by the Heritage Foundation[1] which is a keyhole glimpse into the chaos of this last week and in the years to come. The section relevant to this action is chapter 14 which describes each HHS division as maligned, woke, and in need of reform.
A less nuanced answer is the HHS/CDC made Trump look bad in handling the COVID-19 pandemic and so they’re now ordered to say nothing about anything ever again.
The freeze will be lifted once RFK Jr. is approved by the Senate. The purpose is to stop progressive ideologues in the agencies from doing things in protest of their new boss.