Is Dr. Mahathir's presence in the elections campaign an asset or liability?

He appears to be an asset to BN, according to Malaysiakini's headline:

'Pop star' Dr M's first gig in Bukit Gantang
After a long hiatus, the former premier returns to the campaign trail and there's a buzz in Bukit Gantang over this presence. Mahathir is in town to lend support to the BN ahead of tomorrow's by-election.MORE

Muhyiddin: He's like a pop star!
Enthusiastic response from crowd

But the Chinese has one term which fits Tunku Aziz's 'megalomeddler' and that is, 'Khau Si Khuan'!:

Lim Kit Siang: Tunku Aziz: Do Mahathir A Favour: Ignore him
For UMNO in particular, any attempt at open reconciliation with Mahathir, the ‘megalomeddler’, (a new word I have just invented to add further to the richness of English) will be the kiss of death. If, in the intoxicating afterglow of their 59th general assembly UMNO leaders were disposed to be generous towards Mahathir, and forgive him all his transgressions and sins against society, they need to have their heads examined.

Based on what we know about the man, Mahathir is happiest when he is also at his mischievous best. If there is no crisis, Mahathir will see to it that one is invented. He survived 22 years in office by playing on, and manipulating shamelessly, our fears of a recurrence of the May 13 incident which nearly tore this nation apart in 1969. It is a card that some UMNO types at good at pulling out of their pack when they feel threatened by challenges to “ketuanan Melayu.”

A picture paints a thousand words... and according to this picture, reconciliation between Dr. Mahathir and Pak Lah is at the 'ET' stage.