If my analysis of your described procedure is correct, for the time being after addition of aq. HCl you will have a 2-phases system, with pyridine x HCl in the aqueous layer, and the pure acid in the etheric layer.
phase separation and removal of the ether gains your product
replacing diethylether with THF in this case will FAIL , as THF is highly miscible with water
--> no phase separation
methylenchloride might be the better alternative (with respect to flammability), though I would suggest a hood nonetheless, due to its adverse health effects
regards
Ingo