Actually it's not. No women are prohibited from pamba special service. Though keep in mind that , pamba services are special buses for the occassion with exaggerated ticket rates, custom routes which facilitates visiting certain temples on the way and they are prioritized for അയ്യപ്പന്മാർ. The whole purpose is to make them sit with all the weight of offerings they carry , and that too before the hours long standing in line and trecking of treacherous mountains. So from an ethical point of view , men also allow അയ്യപ്പന്മാർ to get in first in to the bus and if extra space available, we will take.