The parkash of Sanchian, despite being Gurbani, is not considered as a single saroop of Sri Guru Granth Sahib Jee Maharaj, therefore the maryadha for keeping Sri Guru Granth Sahib Jee in a home does not apply. If it was a single saroop, then obviously it would not be right. Sainchian have been used for teaching and learning Gurbani for many years. Sanchian should also not be kept on top of each other at home, but should be kept side-by-side.
Despite the maryadha not applying here, we should have enough respect for Gurbani to treat any gutka, sainchi etc with the utmost respect. Sainchian should not be Parkash when unattended to or not being read. Respect should be out of love and reverence more than anything - not only maryadha. Every letter of Gurbani is Guru ang so the more respect, the better.