That is not the law.  And it has not been the law for the past 30 years.  Once a person is physically in Canada then they must have their refugee claim assessed as a matter of fundamental justice (our version of due process).  That was set out by the SCOC in Singh v Canada [1985] 1 S.C.R. 177;

"Per Dickson C.J. and Lamer and Wilson JJ.: 

Appellants, in the determination of their claims, are entitled to assert the protection of s. 7  of the Charter  which guarantees "everyone ... the right to life, liberty and security of the person and the right not to be deprived thereof except in accordance with the principles of fundamental justice". The term "everyone" in s. 7  includes every person physically present in Canada and by virtue of such presence amenable to Canadian law. "

If the refugee claimants are determined to be economic migrants and not Convention Refugees after their hearing then they will not be protected persons and subject to removal.