You are totally correct on this. Without being able to define a Virtual Wall you could not create a foundation bolt. I found in the SOLIDWORKS Corp Knowledge Base that explicitly states that Virtual Walls are not allowed for use in nonlinear analysis (S-056886). So, it would appear that the option for creating a foundation bolt is not properly locked out within bolt definitions for nonlinear.
If you wish to still move forward with your analysis you could create a block with corresponding holes to represent "ground" and use non-foundation bolt definitions (along with No Penetration contact) to connect the two objects.
Thank you for your answer Ryan,
I'll try to calculate it as you've described - with stiff block.