  We put forward an alternative way to estimate the deconfinement temperature
in bottom-up holographic models. The deconfinement in AdS/QCD is related to the
Hawking-Page phase transition, in which the critical Hawking temperature is
identified with the deconfinement one in the gauge theory. The numeric
estimation of the latter is only possible when the parameters of a $5D$ dual
model are previously determined from consistency with other physical aspects,
standardly, providing a description of the QCD resonances. The traditional way
to fix parameters in the simplest AdS/QCD models is to reproduce the mass of
the $\rho$ meson or the slope of the approximate radial Regge trajectory of the
$\rho$ excitations. Motivated by a general idea that the slope value originates
in gluodynamics, we propose calculating the deconfinement temperature using the
trajectory of scalar glueballs. We consider several holographic models and use
the recent idea of isospectral potentials to make an additional check of the
relevance of our approach. It is demonstrated that different models from an
isospectral family (i.e. the models leading to identical predictions for
spectrum of hadrons with fixed quantum numbers) result in different predictions
for the deconfinement temperature. This difference is found to be quite small
in the scalar glueball channel but very large in the vector meson channel. The
observed stability in the former case clearly favours the choice of the
glueball channel for thermodynamic predictions in AdS/QCD models. For a
balanced approach, we argue that either assuming $f_0(1500)$ to have a
dominating component of $0^{++}$ glueball or accepting the idea of the
universality in the radial Regge trajectories of light non-strange vector
mesons one can reproduce the results for the deconfinement temperature obtained
before in the lattice simulations in the background of non-dynamical quarks.
