We had this discussion recently... and IIRC, it ended with Jeepgod challenging everyone to find out what's being used in most of the operational aircraft in the world today... AL
Very true, but:
Aircraft get pre-flight, 100-hour and annual inspections, and more.
The tubing is supported by structural components frequently along its run.
The tubing layouts are designed by engineers who have studied that sort of thing in airframe applications.
The material is spec'd by engineers who ditto.
The material is certified by the manufacturer to conform to spec.
And finally, light weight is an important consideration.
Not a single one of those conditions apply here, so I wouldn't use it. Especially in this case where there are un-mounted vibrating components, and the tube is carrying gasoline under pressure next to the engine. The only factor in its favor is that it's easy to work with.
On the other hand, it will likely never cause a problem. But on the third hand, if it does ever cause a problem it will be a particularly nasty one,