Gove has more baggage than Heathrow.
He's obviously not alone in that, but although we may consider him a rightwing horror (which he undoubtedly is), he's also got tendencies to be what in the Thatcher days they used to call a "Wet". See his recent record in office:
After the 2015 general election, Prime Minister David Cameron promoted Gove as Lord Chancellor and Justice Secretary in his newly formed Cabinet.[89] He was praised in December 2015 for scrapping the courts fee introduced by his predecessor, Chris Grayling.[90] The fee had been heavily criticised for, among other things, causing innocent people to plead guilty out of financial concerns.[91] Gove also removed the 12-book limit on prison books introduced by Grayling, arguing that books increased literacy and numeracy, skills needed for making prisoners a "potential asset to society."
https://en.wikipedia.org/wiki/Michael_Gove#Secretary_of_State_for_Justice
So they could end up with the worst of all worlds - a rival to Boris (also under suspicion for relative liberalism on some social issues, inasmuch as he's consistent on anything) who fronted the Leave campaign with no Plan A if they won, isn't sufficiently rabid on certain issues to satisfy the right (though that could obviously change for expediency), pretty incompetent in the roles he's held (not necessarily a bar), and utterly unappealing to disaffected voters who've defected to UKIP, let alone likely a high proportion of the electorate.
Last I saw, though it's very early days yet, May was streets ahead of the declared field.