To suppress Hubspot companies or deals, in your account settings you’ll have to configure your hubspot company suppression list
It turns out hubspot can and does synchronize deals stage with company lifecycle stage. Using this, you can configure Sona's company suppression integration with hubspot to avoid contacting current opportunities or customers.
Here's a link to hubspot's knowledge base as to how to set up the synchronization (which is enabled by default).
Once deal to company sync is enabled in hubspot, if not already the case, you'll be able to configure the hubspot company suppression under your Sona account settings.