Hi,
I wouldn't worry too much about redirecting it to the normal site. It has lousy content at the moment, but the moment you take ownership, you'll redirect it to your site with quality content. Anyhow, Google will see that the ownership has changed as the DNS records are changing, there will be a new owner in webmastertools, the content is changing etc.
As it is a typosquatter, he will probably not have put the effort to build (cheap & spammy) links to this domain, and will not have done many efforts regarding SEO - so probably from an SEO perspective this is probably a quite clean site.
You could put the domain a few months in quarantaine to be sure- putting a static html page like 'did you want to visit mydomain.com - click here', activate webmastertools, check the linkprofile, see if any warnings from Google are coming.
If everything looks ok after a few months, you just activate the redirect
rgds,
Dirk
Update: noticed to late that the robots.txt is blocking googlebot - so Google officially isn't aware that the site is linking to low quality site - so would not have too many doubts on redirecting