Under the official terms each eligible joining spouse or child is priced separately, so she can be excluded now. Adding her later would be a family-based petition by a permanent resident, with its own wait and procedure, and she would have the same residence obligations once she immigrates.
Later is possible, and later is slower
The published Gold Card framework prices family members individually, which means an applicant may proceed alone. If he does, and later wants his wife to join, the route is the ordinary family-based one: a permanent resident petitioning for a spouse, subject to the preference category's visa availability shown in the monthly Visa Bulletin, and then consular processing. That can take considerably longer than immigrating together, and it depends on him maintaining his own residence in the meantime, which is difficult if she and the home are in Saskatchewan.
It also raises the question addressed elsewhere on this page: a resident whose spouse, house and business remain in Canada is exactly the profile that suggests abandonment. If the family's real plan is that she stays for some years, the couple should consider whether either of them should be a permanent resident yet, or whether a nonimmigrant route serving his business travel would fit better. Children, if any, must be unmarried and under 21 to be included.