I think "10th March" is not the date of arrival. He signed the card on the 10th, but that was filled out
before arrival - he booked his ticket on the 10th (note that the card is countersigned by the booking agent). His ticket was for the Minnedosa, which left Liverpool on the 19th March and arrived on the 29th March, so he was not in Canada for that long.
The stamp in the top right corner of his card (front side) is cut off but is almost certainly "Rejected"
On the other side:
Sec (or Lec?) SS4 8920?
Also a stamp as rejected, 8th April 1921
http://www.bac-lac.gc.ca/eng/discover/immigration/Pages/thematic-guides-deportation-1893-1977.aspx - it seems most of the individual case files have been destroyed but there might be some summary records
The "Sec ? SS4" note may be a reference to the immigration acts and the grounds on which he was removed, although I can't work out what this refers to exactly. It seems like it should be section 3, SS and then a letter
https://pier21.ca/research/immigration-history/immigration-act-amendment-1919The manifest for the Minnedosa (separate from the cards) is also online:
http://www.bac-lac.gc.ca/eng/discover/immigration/immigration-records/passenger-lists/passenger-lists-1865-1922/http://central.bac-lac.gc.ca/.item/?id=CANIMM1913PLIST_2000908422-00189 - interestingly here he is not marked as detained as some other passengers are
He was also sailing cabin class!
On the same ticket with him are a Mary Sinclair Brown, housewife, and a Charles Brown, child (crossed through - did not sail?).
Mary Sinclair Brown's file (t-14973 pages 3504/5) shows she was also deported - her ref is Sec3 SSj which is section 3 subsection(j) - likely to become a public charge.
Her card makes some of his details more obvious - they both have "PC 2930" as the reference, this can be found here, it came into force in 1920:
https://www.bac-lac.gc.ca/eng/discover/politics-government/orders-council/Pages/search.aspxI. and C. [Immigration and Colonization] - Immigrants of the mechanic artisan or labourer classes landing in Canada must have $250.00 and transportation etc - Min. I. and C. [Minister of Immigration and Colonization] 1920-11-27
So the answer is fairly simple - he said he had $200 but had $170 on arrival, and possibly did not have a pre-purchased train ticket across to Winnipeg. They decided he was covered under the above order and deported him for not having enough funds.
She had even less, although she did say she had a husband in Winnipeg... but possibly they were unable to contact him or get him to send money for her train ticket.
But why are they listed together?