Bad advice based on what? A general disclaimer from a manufacture's website thats clearly their to cover their @$$. Roofing hammers come with disclaimers also, carpenters still use them though.
Cleaning a fretboard with Murphys oil soap with some warm water on a damp rag and wiping it down is bad advise? I didnt recommend soaking the neck in a bucket of water. I didnt recommend to the OP using Murphy's Oil Soap on their guitar period. I stated it was what I used.
Straight from the Ernie Ball website. A demonstration video clearly using Murphy's Oil Soap. Its even used on a signature model that has a wax finish on the neck.
water in wood swells the wood.....on a fretboard, that is BAD for a plethora of reasons.
Bad advice based on what?
Based on the manufactures instruction (not a disclaimer).If a manufacturer says "Don't use this product on unfinished or waxed wood" who's advice do you take? The manufacturer that knows the product inside-out, or an EB tech that (possibly) has no idea how it's made or why not to use it. For me, that's an easy decision.
If this method is your favorite Go for it!! I truly have no issue with you doing what you like......it's your guitar!! I do worry when you put out that this is an acceptable method to other players. IT IS NOT ACCEPTABLE. When giving advice to less experienced people, even in the guise of "this is what I do", it's always prudent to err on the side of caution and if your not 100% positive that your method cannot hurt another persons gear, it's best to say nothing.
Not that it makes a difference, but the spray cleaner used in the EB vid is cut with lemon oil........they've recently switched to orange oil for the same product. Either way...neither is cut with water. FWIW....warm water is even worse....it sinks into your fretboard even faster and deeper.....it would need AT LEAST a solid 24 hours to dry. Conditioning before that will likely seal in that water. If you don't like citrus based cleaners, thats understandable. Citrus oils can break down lacquer finished if not thoroughly cleaned....something I failed to mention in my own post. There are PLENTY of products available that contain no water or citrus. Maybe you'll want to look into them for your own benefit.
BTW....I've been a carpenter for 31 yrs. We don't use roofing hammers....roofers do.
typical roofing hammer:
typical carpenters (framing) hammer: