@Liam1503 Your host is doing nothing wrong. YOU do not intend to complete the August 2020 booking, YOUR choice. So going by the rules, YOU cancel & you get 50% back (but lose service fee) & the host keeps 50%. THAT'S the rule, you accepted when you booked!
It might be as @Mike-And-Jane0 say, allowing you back next year off platform for 50% of normal charge (cos he got the other 50% THIS year) would be doing you a favour, saving BOTH of you money in commission fees. It's NOT shady; many hosts let on multiple booking sites & through private arrangements. THIS booking has been made through Airbnb, whether you travel & stay, or accept the 50% refund.... NEXT years booking is not part of this.... once you've stayed this August or got a refund your Airbnb contract is over.... Airbnb does not own the relationship between host & guest forevermore, once the CURRENT booking is concluded. So your host is doing nothing wrong in suggesting a private arrangement in future.... And if he doesn't honour it next year, you've still lost nothing, cos the cancellation policy states you get 50%/host gets 50% when you cancelled this year.
It all boils down to you being angry (& vindictive) cos you're not getting your way... And you're losing money, not cos the host is bad, nor shady, but because the RULES of the cancelation policy say the host is entitled to 50%! - Your bad!
You may yet be lucky.... If you hold the booking a bit longer, the EC policy may be adjusted in your favour!
P.S. Please try to see things from the host's point of view..... Please don't be malicious & vindictive, nor an entitled customer, - we're a community, remember?! 😉