If the sellers WANTS us to do this.. what harm is there?

Harming your credit if your bank doesn't provide any type of deferral is going to hurt more in the long run.  

Also they may be sympathetic to the tenant and not allow you to throw them on the street with no where to go.We as landlords are not in a good position.If you do get a court date tell the judge about your bills pilling up and how you can't pay the mortgage and that this may cause irrevocable harm when you get foreclosed on or owe extra fees and penalties at best.

Recessionhttps://www.ocregister.com/2020/03/16/coronavirus-pushes-u-s-into-recession-california-to-be-hit-hardest-ucla-economists-say/Oilhttps://www.biggerpockets.com/blog/coronavirus-harm-real-estate-market-oil-price-warCovid-19https://www.kcra.com/article/newsom-more-than-half-of-california-projected-to-contract-covid-19/31791343#We are in a systematic designed destruction of the world economy, the FED [and all central banks in the world, follow same gameplan] is going to become the buyer and seller of last resort.

Both of these programs are designed to promote economic growth in communities, and the National Association of Realtors® made the case that investors in these programs should not be harmed due to the effects of COVID-19. 1031 Like-kind exchanges.

fbclid=IwAR1_ej9w4ehy8nk1tbQqymMiVDJRd38X44AfzFGeHUXqavYaeZW7aitYJ3MProtections granted to residential renters during COVID-19 crisisGovernor Lamont’s order – Executive Order No. 7X – includes a provision taking the following actions to protect residential renters during the public health crisis:All landlords are prohibited from issuing a notice to quit or beginning eviction proceedings before July 1, 2020, except for serious nuisance, such as physically harming another tenant or the landlord.For rent due in April 2020, landlords must grant tenants an automatic, 60-day grace period for payment, instead of the existing 9-day grace period.For rent due in May 2020, landlords must grant a 60-day grace period for payment upon the request of tenants.

At the same time, the first tenant (let's call them tenant A) feels like they are in harms way. 

Although the idea of ten thugs sounds like fair justice, it could also be seen as assault (threat of harm).

I've had them do much more harm than good.

As for the buy now or wait, as @Adam Tafel mentioned, the harm in waiting is you continue to pay rent currently, which is money out the door (meaning minimal in the grand scheme of things).