The box is being used as a junction box, so yes, it is not uncommon to have multiple neutrals ( and hots) tied together there. Today, you'd find a wire nut or crimp on those wires...just twisting them together is not great, and that could be an issue. The only issue may be the box fill requirements...the size of the box must be sufficient for the number of cables coming in. Without knowing the actual volume of that box, can't say if it meets today's code. Last, not all boxes are rated to hold a ceiling fan. If it was not rated for that, you risk having it pull the whole thing loose and fall down on top of you.