I don't know what the laws regarding kicking out tenants in the Phillipines are, but I'd hate to be the landlord locked into this lease if the price of bitcoin drops significantly.
Or the the renter stuck paying if the price of bitcoin goes up massively. (and would that count as an increase in rent if there is any sort of rent control or limitation on how much rent can increase by?)
The same could happen with any currency (and does). Your rent would not fluctuate if the price of cars/tvs/food went up in the middle of your contract.