I agree, the announcement is a little bit of a word salad. The whole Delaware example was differentiating a state with no reciprocal agreement to contrast its tax treatment as compared to states with a reciprocal agreement with Maryland. I would read that sentence as "compensation paid to a Maryland nonresident who is teleworking from Maryland is Maryland-sourced income, and therefore, subject to withholding."
In other words, if you are not a Maryland resident or a resident of one of the states that have a reciprocity agreement with Maryland but are working from Maryland due to temporary circumstances, your income is taxable by Maryland. You never worked from Maryland in 2021, so your income is not sourced from Maryland.
