Is the Hajj considered legally acceptable if the pilgrim fails in his duty to care for the pilgrims and to guard them?

If you go with a Hajj delegation with the intention of working and performing Hajj, there is no harm, as long as your performance of the rituals does not lead to a dereliction of your work. This is because commitment to work is an obligation, and betrayal of trust is forbidden. If it is possible to combine work and rituals without detriment, then Hajj becomes obligatory for you. However, if it is not possible to combine them, then Hajj is not obligatory for you at that time, and it remains a fard (religious obligation) upon you until you are able to perform it. This applies to the obligatory Hajj. As for voluntary Hajj, it is not obligatory. If you contravene and perform Hajj while neglecting your work, the Hajj is valid, but you will incur sin for the dereliction of duty.