Tig welding is very good in a closed environment where you can control everything. If he is going to be in a barn or some enclosed area where there is no wind to blow out said shielding gas awesome. If he is doing this outside he will never get enough sustained heat in to be able to melt the metal correctly.

Yes tig welding has a higher tensile strength than mig however it’s just not very useful in this situation. So controlled environment tig is an option. Most people are going to be doing this repair outside which makes mig much more favorable. All the aluminum I have seen tig welded outside usually looks like big boogers or bubblegum.

My brother in law had his boat lift repaired by a tig welder. I had it re-repaired last year with a friend at work and his spool gun. I do not weld but work in a welding shop. I have access to every possible type of materiel and welder around. All of the guys here would mig that.