Answer:
To answer both of your questions at once and clear up any confusion: IM Epinephrine should be considered for patients with severe respiratory distress with cough due to an acute asthma exacerbation. IM Epinephrine for bronchoconstriction is restricted to patients < 50 years).
The most recent Feb 22 Considerations Memo (here) describes the rationale behind restricting it to those <50 years. But, as you point out, does not describe when to give it. The most updated memo that describes when to consider IM epinephrine administration is from Jan 4th, 2021 (here).
The requirement for BVM ventilation was removed when the Considerations were formulated, in order to reduce potential aerosolization of the virus. The thought is that IM epinephrine administration, in the appropriate patient population, may reduce the bronchoconstriction enough to negate the need for aerosol-producing BVM ventilations or aersolization.