In any case, Azure and AWS are complying with the same sanctions without a blanket ban. After all, they are American companies as well. Azure and AWS don't allow customers from Iran to purchase hosting services, but don't block access to all sites hosted on their platforms, and it seems that this is enough for US regulators to not consider them in violation of sanctions. I imagine Google has taken an extreme "better safe than sorry" approach which other players have fortunately decided not to copy.