An instructor does not log flight time.

He logs instruction given and he logs PIC time. None of my log books have a
column for "flight time".
Because it is legal to log PIC time for the time during which flight
instruction is given, he is able to log PIC time even if he never acts as
PIC, and even if the aircraft never leaves the ground, thus, he can log PIC
time when he isn't flying and he never logs "flight time".

The fact that the instructor is physically in the airplane does not mean
that the instructor is acting as PIC. The fact that the instructor is able
to log PIC time for that time he gives flight instruction does not mean that
the instructor has to act as PIC in order to log that time.

The fact that the instructor sits in the airplane and that flapping his arms
provides no significant lift is proof that the instructor is not flying,
only the airplane is flying, the student and instructor are acting as
pilots, in one form or another.