The answer is in the question itself. If the priest has “recommended” it, in language which is clear that it is a recommendation only, then it is not sinful, in itself, to not follow his recommendation. Of course, this is not a license to do something which is sinful by other standards (eg. If I don’t follow my priest’s “recommendation” to avoid fornication I have still committed I mortal sin!), but, there is no sin of disobedience or disrespect in not following a recommendation which was not issued with authority.
As a general rule, treat the priest’s guidance with respect, and don’t discard it without a reason, but, if you decide to not act on it then there is no sin (of disobedience or disrespect).
Note, the question is, “Is it a sin”. That is all that I have addressed. Whether or not we **should **follow a priest’s recommendations is another question. But it is not, in itself, sinful. It is nothing that would prevent me from receiving communion, or something which I should confess.