"Buddha summarised his entire teaching in one sentence, namely:...

"Buddha summarised his entire teaching in one sentence, namely: "nothing whatsoever should be clung to"

that is absolutely 100% wrong as well

some 'things' should be clung to!
if you are climbing a ladder then you would be foolish not to cling to the rungs.
discernment comes into play when you understand when, and what, to cling to, and when to release.