You are mistake ...only a small part of kerala was muslim due to traders and the harassment of Namboodiri Brahmins. Vast majority became muslims due to the effort of tipu sultan.
Tipu Sultan destroyed more than 8000 temples in Kerala, Mysore and Tamil nadu. In 1788 Tipu Sultan had razed Calicut to the ground. Tipu spared Raja of Cochin as he was a vassal of Hyder Ali.
Tipu had thousands of people killed in Kerala. They were hung upside down on trees , before being put to the sword and then left to hang there , with terrible stench everywhere. Elephants were used to tear bodies apart. Tipus soldiers raped at will.
They used to line up thousands of Hindu men to get circumcised stretch out the foreskin, slice with a knife and outnext guy! Then they had to eat beef while bleeding from the tip of the penis, wrapped in a rag.
When thousands of Hindus ran away into the forests , Tipu gave his royal word of honour to come back and he would forgive them. As soon as they came back attractive women would be caught as slaves, men and children would be given the optionbe killed or get yourself circumcised now! This happened to Kolathiri Raja and he preferred to be pulled apart by elephants than eat beef.
While escaping from Tipu's army, one of the princes of the Chirackal Royal family in North Malabar was captured . As per the accounts of Tipu's own diary , the body of the prince was dragged by elephants through his camp and it was subsequently hung up on a tree along with seventeen of his followers who had been captured alive
Letter written by Tipu Sultan dated January 19, 1790, to Badroos Saman Khan: "Don't you know that I have achieved a great victory recently in Malabar and over 4 lakh Hindus were converted to Islam. I am now determined to march against that 'Cursed Raman Nair' without delay. (Reference is to Rama Varma Raja of Travancore State who was popularly known as Dharma Raja for giving shelter in his state to all those who fled Malabar.). Thinking that he and his subjects would be soon converted to Islam, I am overjoyed and hence abandoned the idea of returning to Srirangapatanam."
Only if the men got circumcised, the family would be spared. Today hardly any Kerala Muslim in Malappuram district know that their forefathers were the same Hindus who stood crying in line by the thousands to get their foreskins sliced off by a crude knife. 25% of Keralas population is Muslim today. You get a general idea of how many Hindu men got circumcised and how many got killed.
Tipu Sultan got his own son married to Mappila Arakkal Biwithe Queen of Cannanore. This was to score brownies points over Nizam of Hyderabad who had refused to give his daughter to a man of poor lineage as Hyder Ali was a Punjabi commoner, not of Mughal descent
Funny part was when ever Tipu Sultan went on a campaign he used to consult Hindu astrologers at Ranganatha Swami Temple at Srirangapatnam. He also consulted the Hindu astrologers at Lakshmikanta temple at Kalale.
Tipu also renamed all the towns with Islamic names. In Kerala Kozhikode became Islamabad. Today only Feroke retains the old name. Rest have all been named back to original. British changed Kozhikode again to Calicut. Today once again it is back to Kozhikode.
Here is a list of ancient temples looted and desecrated as per British records: Triprangot, Thrichembaram, Thirunavaya, Thiruvannoor, Calicut Thali, Hemambika Temple, the Jain Temple in Palghat, Mammiyur, Parambatali, Venkitangu, Pemmayanadu, Tiruvanjikulam, Terumanam, Vadakhumnnathan Temple of Trichur, Belur Siva Temple, Shri Veliyanattukava, Varakkal, Puthu, Govindapuram, Keraladhiswara, Trikkandiyur, Sukapuram, Bhagavati temple Kodungallur, Maranehei Temple of Aaalvancheiri Tambrakkal, Vengara Temple of Aranadu, Tikulam, Ramanathakra, Azhinjalam Indiannur, Mannur Narayan Kanniar and Vadukunda Siva Temple of Madai.
The biggest loss was the 7000 year old Thirunavazha temple, along with priceless Vedic records. This temple was even older than 6000 year old Guruvayur.
BTW in Tipu was so secular that Muslims in his kingdome did NOT have to pay taxes