At the 12:10 mark in the Google hangout from yesterday, John Mueller said he met with the team yesterday about the Intrusive Interstitials Mobile Penalty that is coming in a few months and he said that right now, the penalty only applies to what happens "the interaction between the search click and going through the page and seeing the content."
So what happens after that, such as an on-exit interstitial or several clicks later an intrusive interstitial comes up, John said that is between you and your user - not Google.
Here is the video embed at the start time:
Here is the transcript:
Webmaster: So are you familiar with the webmasters Google blog posting that mobile interstitials are going to be penalized from Google search?
John Mueller: Yes
Webmaster: We have we have this ad that spawns sort of a full-page interstitial on exit intent. I can provide a link so you can see what it looks like. I’m basically try to close it will , you've seen those? Those are common. The question is are those, do those fall into the full page or interstitial ah definition?
John Mueller: We just talked about that with the team last couple of days.
So at the moment those wouldn't count. What we're looking for is really interstitials that show up on the interaction between the search click and going through the page and seeing the content. So that's kind of the the place we're looking for those interstitials. What you do afterwards like if someone clicks on stuff within your website or closes the tab or something like that then that's kind of between you and the user.
Forum discussion at Google+.