Dont take advantage of a situation. If the landlord did something that caused the gym to close, i would agree with you (somewhat). But that is not the case.
This is a very "landlord-centric" view of the world, and I'm not sure it's appropriate. As a matter of fairness / justice / what's right, why is the loss on the tenant unless the landlord "did something"? Why not the opposite -- why isn't the loss on the landlord unless the tenant "did something"? Why aren't they required to share in the loss and compromise? Why do you feel that a tenant who is experiencing some economic hardship himself is "taking advantage" of a situation by seeking not to pay for a service he can't use?
And, again, the landlord -- along with all the other homeowners -- are in the best position to "do something" about the problem, i.e., protest to their HOA that they're being charged fees for services they can't use when no money needs to be spent on cleaning, mantanance, etc.
Of course, we have laws and contracts to resolve most of these questions, so we theoretically get to avoid the "moral" side of these questions. But for one, we're in a new and unprecedented situation that might not be so easily resolved by laws and contracts, and the "moral" side is highly relevant. And the relevant decisionmakers, for better or worse, don't necessarily care about the letter of the law and will operate on their personal sense of fairness and justice.
if you are leaving anyways, he gains nothing by pleasing you. Withhold rent and he'll deduct from your security at the end of the term. Dont pay last month, and he'll commence a collection case on you.
Also, I'm not AT ALL saying we're going to do that, but just to address your if we unilaterally withheld a total of a couple hundred bucks and didn't pay last month so as to avoid him deducting it from our security deposit, the idea that "he'll commence a collection case on you" is highly farfetched. He first has to file a lawsuit, win the lawsuit, and get a judgment before he can collect anything. The landlord is unsophisticated; he's not going to hire a lawyer, pay a $500 filing fee, deal with an aggressive tenant who will fight the lawsuit, etc. over a couple hundred dollars in a lawsuit where there are decent arguments to be made on both sides.
Lastly, how would he know we're leaving? He doesn't.