I hate to give government agencies the benefit of the doubt, but perhaps its because they have not identified myclobutanil as the cause of the problem (yet). The CDC and the FDA say their investigation is in progress. Here is what they claim they are currently doing:

Laboratory Testing:

• CDC and FDA are expanding the range of available laboratory testing.
• CDC is currently testing bronchoalveolar lavage (BAL) fluid samples, as well as blood or urine samples paired to BAL fluid samples.
• CDC is testing pathologic specimens, including lung biopsy or autopsy specimens, associated with patients.
• CDC is offering aerosol emission testing of case-associated product samples from e-cigarette, or vaping, products and e-liquids. Analysis of aerosol emissions will augment FDA’s ongoing work to characterize e-liquid and will improve our understanding of exposure among case-patients associated with the Lung Injury outbreak. CDC is coordinating e-cigarette, or vaping, product analysis with FDA.
• Results may provide insight into the nature of the chemical exposure(s) contributing to this outbreak

https://www.cdc.gov/tobacco/basic_information/e-cigarettes/severe-lung-disease.html#what-cdc-is-doing

You say that the CDC is telling people to only use government products, but that is incorrect. They recommend people stop vaping entirely, regardless of whether the vape product is legal or illegal.

CDC recommends that you do not use e-cigarette, or vaping, products that contain THC.
[...}
Since the specific compound or ingredient causing lung injury are not yet known, the only way to assure that you are not at risk while the investigation continues is to consider refraining from use of all e-cigarette, or vaping, products (see link above).

The information coming out from both the government and the media is confusing and not particularly helpful.