The [sic] is just wrong. Ultimately, whoever wrote this seems to just not know what he's talking about. "We got" is incorrect, so [sic] after both instances of that would make sense. Others have pointed out that 93 is the incorrect age, so [sic] after 93 would make sense, too. "Are of 60 years old" is incorrect, so [sic] after "of" would make sense.
In short, whoever wrote it seems to be a non-native English speaker. The quotation is full of errors, but "who's" is definitely not one of them.
Phrased in "proper" English, this tweet might read as follows:
"We have a PM who’s 93 years old. We have a team of eminent persons to repair the economy who are all over 60. I guess that 'I’m too old for this s***' is no longer valid."
Edit: Others have pointed out in the comments:
- "We got" is proper English if this is interpreted to be in simple past tense. This is true. I will leave my previous answer alone, but agree that you could retain "We got" and it would be proper past tense. If the tweet weren't full of other odd errors, I would be more likely to interpret it as proper past tense, I think.
- Even in present tense, "we got" is idiomatic. However, professional newspaper editors often use [sic] with nonstandard grammar, as well, even when it is idiomatic.