Dryer Venting through Roof

[mountainjim]

I have a gas dryer which was venting into the garage. Decided to discontinue that due to not wanting CO or mold accumulation. There's another vent in the laundry room that I've connected the dryer to which vents straight up to the roof. Home inspector says this roof vent presents a fire hazard due to using a cap not normally used for dryer vents (see pic). I've been up on the roof and the cap appears to be a 4 inch gas vent cap that's typically used for venting gases but not dryer lint. Also it appears this cap cannot be removed from the vent pipe without cutting it (screws in the cap appear to be machined into the pipe and not removable). Air flow appears to be good on the roof and it seems like lint is able to escape through the opening although occasionally small pieces will catch in the corners of the vent before breaking free. I have two questions...

1) Can I leave this cap as is?

2) If I leave this cap can I reduce any fire hazard risk by cleaning the vent from inside the house (since cap is irremovable wouldn't be able to do it on roof) with a rotary dryer vent cleaning system?

Thanks!