I don't think many/any foundation (or similar entity that accepts donations) is ever going to be willing to give refunds in the way that you request.
I find "traditional establishments would never do this" to be a particularly uncompelling argument within the bitcoin space. The whole point of bitcoin should be to NOT make the same mistakes of traditional institutions.
From this perspective, the foundation has failed so far. When their chief scientist abandoned them, and stated reasons like lack of transparency, that was a major red flag for me - and should be for any bitcoiner.
Any establishment/institution still needs to follow the basic principles of economics. It simply does not make any sense for TBF to refund any donation they have received as they have already budged for the money they have been given.
I am certainly not defending any of their actions, as I am not in any way a supporter of them, but I do think that to ask to have donations refunded would be something that is very unlikely.
If Bitcoin is the new paradigm in showing the world how a better system of things could improve their lives, and TBF has opted to be the governing body that speaks in behalf of that swift, then wouldn't it have been wiser of them to simply honor one refund, whereupon two to three more memberships would taken their place due to their kind gesture? The alternative is categorically state fuck you and the horse you came in on, thus amassing more discontent, then having to conduct an AMA on Reddit to save face after most its venerable members have flew the coop with the hope of future revenue flowing in to stay afloat.