They specifically removed the text on the website saying you can get API access from feeding, replaced this with a link to their paid RapidAPI (under "Enthusiast Usage Terms") and no longer automatically give you API access with an active feeder key. That seems like a pretty clear message even if they made an exception for you. Besides, how long do you think your free access will last under the new ownership?
EDIT: In their FAQ it currently states: "In very limited situations ADSBexchange.com may choose to allow non-profit, research, or educational entities access to the historical data or API at reduced fee, in these situations such entities must meet all other requirements including hosting a feeder. ADSBexchange.com API pricing is a fraction of the cost of ADS-B data available anywhere else." To me that is quite different than their previous policy of providing automatic noncommercial API access to anyone hosting a feeder. It removes an incentive to feed and discourages use of the API.
EDIT: In their FAQ it currently states: "In very limited situations ADSBexchange.com may choose to allow non-profit, research, or educational entities access to the historical data or API at reduced fee, in these situations such entities must meet all other requirements including hosting a feeder. ADSBexchange.com API pricing is a fraction of the cost of ADS-B data available anywhere else." To me that is quite different than their previous policy of providing automatic noncommercial API access to anyone hosting a feeder. It removes an incentive to feed and discourages use of the API.