i have provided evidence, what more do u need
The only Malagasy concerned by a possible Somali influence are some coastal people like the Antemoro, especially the Anteony(aristocrats) and Antalaotra(scribes, diplomats)clans as both claim being descendants of foreign Men of Islamic faith.That being said, they don't claim Somali ancestry but Arabian ancestry from Mecca. The Anakara subgroup of the Antalaotra even claim Arabian Jewish ancestry.
Source
Their alphabet called sorabe is based on Arabic and there's a possible Javanese influence(Javanese Muslims had a script based on Arabic too). Apart from javanese, Bantu, Malay and Sanskrit influences are found in the Malagasy language but no trace Somali.
Sorabe alphabet
Now there's the genetic part. From this study
Genetic study Antemoro
This graph show the Paternal haplogroups(Ydna) of the three different Antemoro clans. The Ampanabaka who constitute the majority are mainly of Bantu then Austronesian extraction. The Antalaotra and especially the Anteony lineages are in great part originally from the Middle East(J1, J2, T1) in accordance with their oral and written history. Those T1 could've been mediated by Northern Somalis(Dir, Ogaden..)though as this Y dna is found in high frequency up north but read this statement from the study:
"The Median-Joining network for T1 haplotypes links these lineages to Israel, Lebanon and Palestine. These results are also consistent with the low FST values between Anteony and Antalaotra and populations from Middle East/Southwest Asia. The combination of these two lineages (J1 and T1) tends to converge to an origin in the Persian Gulf or Middle East."
Given the presence of an Arabic derived alphabet amongst the Antemoro, their oral and written history claiming Arabian ancestry, genetic studies confirming it and debunking a huge Somali influence , he can't say Somalis ruled Madagascar lol. Only some Madagascar groups like the Antemoro assimilated significant foreign migrants by the way.
In another study, they found that only 1 out of 133 Malagasy individuals had a Somali lineage and he is from the coastal Antanosy ethnic group(1/52,less than 2%)living close to the Antemoro. Obvious middle Eastern lineages are more numerous:
"The geographic assignment of exact matching and neighboring haplotypes in the YHRD and in our database suggested for J2, R1a1, and R1b1 chromosomes a clear European-Near Eastern origin, for the E1b1b1a chromosome a Somali origin"
Genetic study Madagascar
Sorry to burst your bubble but the Somali contribution to the Malagasy people is very marginal. It's less important than the Austronesian,Bantu, later Javanese and Swahili waves, Arabian, Indian, French influences.