说是不说明白是怕不能投资的工人知道后心里不平衡

to say that it was not made clear because [we] were afraid that the workers not eligible for investing would feel left out after learning the news [truth]

说是不说明白是怕不能投资的工人知道后心里不平衡，因为投资回报很高，等等。
The illegibility (of the investment object) is excused for fear of psychological imbalance of workers who are unable to invest after knowing the fact, for reason of very high repayment, etc.

For your reference...

My interpretation is:
(你可以)说是不说明白(但那就)是(因為the owners, presumably)怕不能投资...
A Chinglishy translation from this interpretation would run:
"You may say that it is unexplained, but that is out of fear that workers unable to invest would be upset after learning of it (the investment opportunity they were not in a position to benefit from)."

The effect of 说是不说明白 is to admit that things have been left without much of an explanation, followed by the excuse, so perhaps:

Admittedly, details have been left vague, but only out of concern that workers who could not invest would be disgruntled if they knew (what they were missing).