The point you overlook in this action Guru is that by using Hack Green, you put a lot more European activators into your range than you would be able to hear because of skip distance if using a local receiver (WebSDR or physical in your QTH). OK, you still need to get your Tx signal to the station in say Portugal but somehow that can be achieved when receiving a QRP activator signal at a distance less than the skip can allow.
In any case - I come back to my earlier statement - SOTA is a personal challenge not a contest where you are competing against others. If you are happy with using a WebSDR (for whatever reason), that is your decision and I don’t personally believe the MT should add any new rules about it. How would it be policed? There could be arguments etc.
Once you have your own remote TX & RX station working again, this problem goes away for you. In the interim, if you are OK with using Hack Green, that’s your choice.
By the way if you do look for other close by WebSDRs don’t forget there are the kiwi SDRs (under sdr.hu) as well as the WebSDR network itself.