The idea is most definitely ok. Although personally I would rather not destroy the cable permanently, but make a USB end, but that’s a detail.
However, generally using 05P is rather a slightly more expensive option compared to the regular DW2.
I use both DW2RF and DW2WIFI, where I desoldered the contact and soldered the cable terminated for my needs with a water level sensor. But the principle of operation is the same, provided that the water/humidity sensor is a reed relay type with an open/closed state.
Of course, it doesn’t look so nice in ewelink when it writes “door” next to the sensor and no zigbee.