True, it’s not forbidden.
Its a caution zone however and not for “normal operations” and it at least appears to have been unnecessary under the described conditions.
Point being, anticipating is part of airmanship.
As soon as you notice ATC is ‘keeping you high’ formulate a plane how to fix it further down the line. Consider upcoming speed restrictions, ATC “expect” instructions ( expect this Arrival, expect direct in 15 miles, expect to follow) yadayadayada.
Like build the picture in your mind.
Ask the other pilot, hey any suggestions on how to fix this?
Then if you expect to be out of options soon as in ATC is putting us in a situation I can’t fix then request a descent or a delay vector.
I fly an absolute beast of an airplane and there are certain things we just can’t do with something the size of an ocean liner.
If you (ATC) insist we descend at 300+ kts then we’ll need half an average European country to slow down.