The type-I seesaw mechanism yields the effective neutrino mass $$m_\nu\sim -M_DM_N^{-1}M_D^T.$$ Here, $m_D$ is the Dirac neutrino mass coming from Yukawa coupling of the left-chiral neutrino with the standard model Higgs. Without fine-tuning the Yukawa couplings in $M_D$ one has $M_D\sim 100$ GeV. Now, if one requires a neutrino mass of the $0.1$ eV, then one must choose $M_N\sim 10^{12}$ GeV.

However, this paper, below eqn. 2.2, says that

However, theoretical arguments based on the naturalness of the SM Higgs mass of 125 GeV against radiative effects induced by the neutrino loop suggest the seesaw scale to be below $\sim 10^7$ GeV.

Is this scale of $M_N$ viable without fine-tuning the Yukawa couplings of $M_D$?

The type-I seesaw mechanism yields the effective neutrino mass $$m_\nu\sim -M_DM_N^{-1}M_D^T.$$ Here, $M_D$ is the Dirac neutrino mass coming from Yukawa coupling of the left-chiral neutrino with the standard model (SM) Higgs and $M_R$ is the mass of the right-chiral neutrino whose scale is not known a priori. Without fine-tuning the Yukawa couplings $Y$ in $M_D=Yv$ (where $v=246$ GeV, the VEV of SM higgs) one has $M_D\sim 100$ GeV. Now, if one requires a neutrino mass of the $0.1$ eV, then one must choose $M_N\sim 10^{12}$ GeV.

However, this paper, below eqn. 2.2, says that

However, theoretical arguments based on the naturalness of the SM Higgs mass of 125 GeV against radiative effects induced by the neutrino loop suggest the seesaw scale to be below $\sim 10^7$ GeV.

Is this scale of $M_N$ viable without fine-tuning the Yukawa couplings of $M_D$?