Use of can "arranging a meet"

I’m using Rymond Murphy english grammar. On unit 25 you can find:

"But can has only two forms, can (present) and could (past). So sometimes is necessary to use (be) able to:

Example: Tome might be able to come tomorrow. (can has no infinitive)"

But in the exercises I found this example:

“I can’t see you on Friday, but I can meet you on Saturday morning”

Why does he use can (present) in proposing a new date?
Would be more correct “I might be able to meet you on Saturday”?

Both forms are fine in your example, and are not related to the problem of ‘can’ having no infinitive or future form.

‘Can meet you’ is less tentative than ‘might be able to meet you’. ‘Can’ is present here (as is ‘might’), and could be replaced by ‘am able to’. All 3 forms express present ability to fulfil the promise of meeting.