Still haven't found anything that definitely connects him to the Empress of Ireland, but in an Ancestry.com database, a John Roberton (this is how it is transcribed, but original record looks like could easily be Robertson) Abercrombie, arrived in Vancouver from Hong Kong on board the Empress of Asia on 3 May 1914. He is aged 25 (born about 1889), born in India, but race of people is English, occupation listed as Merchant, and destination is London and just transiting Canada.
The Empress of Asia, according to Wikipedia is built by the same company as the Empress of Ireland, and also owned by the same company - Canadian Pacific Steamships. So it seems possible he is travelling from Hong Kong to London, via Empress of Asia (train across Canada?) and then boarded Empress of Ireland to go on to London?
The Source information for the Ancestry database is
Ancestry.com. Canadian Passenger Lists, 1865-1935 [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2010.
Passenger Lists, 1865–1935. Microfilm Publications T-479 to T-520, T-4689 to T-4874, T-14700 to T-14939, C-4511 to C-4542. Library and Archives Canada, n.d. RG 76-C. Department of Employment and Immigration fonds. Library and Archives Canada Ottawa, Ontario, Canada.