For several seasons I did this same compressed air process finishing off by running antifreeze through the system as a final step. Belt and suspenders kind of mindset.
Last season I only used the compressed air making sure to blow out the toilet valve, black tank flush and outside shower.
There were NO problems
this spring when I went through the dewinterizing process.
Thanks to the posts on this forum, not going through the antifreeze process saved a bunch of time and hassle on both ends of the winterizing operation.
Getting ready to repeat last year's method here in a few days.